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Post by likeike on Feb 2, 2023 15:30:04 GMT
y @miningstocks on 1 Feb 2023, 14:50
Glossary of Mining Terms
The CEO.CA glossary of mining terms is a comprehensive list of definitions and explanations of technical words and phrases commonly used in the mining industry. It serves as a reference for individuals and companies involved in the exploration, extraction, and production of minerals and other natural resources.
The glossary covers various topics such as geology, drilling, blasting, and processing, providing clear and concise explanations for industry professionals and investors. This resource can be valuable for anyone seeking to better understand the complex terminology used in the mining industry.
A
Acidic precipitation - Snow and rain that have a low pH, caused by sulphur dioxide and nitric oxide gases from industrial activity released into the atmosphere.
Acidic rocks - Igneous rock carrying a high (greater than 65%) proportion of silica.
Acid mine drainage - Acidic run-off water from mine waste dumps and mill tailings ponds containing sulphide minerals. Also refers to ground water pumped to surface from mines.
Adit - An opening driven horizontally into the side of a mountain or hill for providing access to a mineral deposit.
Aerial magnetometer - An instrument used to measure magnetic field strength from an airplane.
Aeromagnetic survey - A geophysical survey using a magnetometer aboard, or towed behind, an aircraft.
Agglomerate - A breccia composed largely or entirely of fragments of volcanic rocks.
Agglomeration - A method of concentrating valuable minerals based on their adhesion properties.
Agitation - In metallurgy, the act or state of being stirred or shaken mechanically, sometimes accomplished by the introduction of compressed air.
Airborne survey - A survey made from an aircraft to obtain photographs, or measure magnetic properties, radioactivity, etc.
Alloy - A compound of two or more metals.
Alluvium - Relatively recent deposits of sedimentary material laid down in river beds, flood plains, lakes, or at the base of mountain slopes. (adj. alluvial)
Alpha meter - An instrument used to measure positively charged particles emitted by radioactive materials.
Alpha ray - A positively charged particle emitted by certain radioactive materials.
Alteration - Any physical or chemical change in a rock or mineral subsequent to its formation. Milder and more localized than metamorphism.
Amorphous - A term applied to rocks or minerals that possess no definite crystal structure or form, such as amorphous carbon.
Amortization - The gradual and systematic writing off of a balance in an account over an appropriate period.
Amphibolite - A gneiss or schist largely made up of amphibole and plagioclase minerals.
ANFO - Acronym for ammonium nitrate and fuel oil, a mixture used as a blasting agent in many mines.
Annual report - The formal financial statements and report on operations issued by a corporation to its shareholders after its fiscal year-end.
Anode - A rectangular plate of metal cast in a shape suitable for refining by the electrolytic process.
Anomaly - Any departure from the norm which may indicate the presence of mineralization in the underlying bedrock.
Anthracite - A hard, black coal containing a high percentage of fixed carbon and a low percentage of volatile matter.
Anticline - An arch or fold in layers of rock shaped like the crest of a wave.
Apex - The top or terminal edge of a vein on surface or its nearest point to the surface.
Ash - The inorganic residue remaining after ignition of coal.
Assay - A chemical test performed on a sample of ores or minerals to determine the amount of valuable metals contained.
Assay foot (metre, inch, centimetre) - The assay value multiplied by the number of feet, metres, inches, centimetres across which the sample is taken.
Assay map - Plan view of an area indicating assay values and locations of all samples taken on the property.
Assessment work - The amount of work, specified by mining law, that must be performed each year in order to retain legal control of mining claims.
Authorized capital - see capital stock.
Autogenous grinding - The process of grinding ore in a rotating cylinder using large pieces of the ore instead of conventional steel balls or rods.
B
Back - The ceiling or roof of an underground opening.
Backfill - Waste material used to fill the void created by mining an orebody.
Background - Minor amounts of radioactivity due not to abnormal amounts of radioactive minerals nearby, but to cosmic rays and minor residual radioactivity in the vicinity.
Back sample - Rock chips collected from the roof or back of an underground opening for the purpose of determining grade.
Backwardation - A situation when the cash or spot price of a metal stands at a premium over the price of the metal for delivery at a forward date.
Balance sheet - A formal statement of the financial position of a company on a particular day, normally presented to shareholders once a year.
Ball mill - A steel cylinder filled with steel balls into which crushed ore is fed. The ball mill is rotated, causing the balls to cascade and grind the ore.
Banded iron formation - A bedded deposit of iron minerals.
Basalt - An extrusive volcanic rock composed primarily of plagioclase, pyroxene and some olivine.
Basal till - Unsorted glacial debris at the base of the soil column where it comes into contact with the bedrock below.
Basement rocks - The underlying or older rock mass. Often refers to rocks of Precambrian age which may be covered by younger rocks.
Base camp - Centre of operations from which exploration activity is conducted.
Base metal - Any non-precious metal (eg. copper, lead, zinc, nickel, etc.).
Basic rocks - Igneous rocks that are relatively low in silica and composed mostly of dark-colored minerals.|
Batholith - A large mass of igneous rock extending to great depth with its upper portion dome-like in shape. Similar, smaller masses of igneous rocks are known as bosses or plugs.
Bauxite - A rock made up of hydrous aluminum oxides; the most common aluminum ore.
Bear market - Term used to describe market conditions when share prices are declining.
Bedding - The arrangement of sedimentary rocks in layers.
Beneficiate - To concentrate or enrich; often applied to the preparation of iron ore for smelting.
Bentonite - A clay with great ability to absorb water and which swells accordingly.
Bessemer - An iron ore with a very low phosphorus content.
Bio-leaching - A process for recovering metals from low-grade ores by dissolving them in solution, the dissolution being aided by bacterial action.
Biotite - A platy magnesium-iron mica, common in igneous rocks.
Bit - The cutting end of a drill frequently made of an extremely hard material such as industrial diamonds or tungsten carbide.
Blackjack - A miner's term for sphalerite (zinc sulphide).
Black smoker - Volcanic vent found in areas of active ocean floor spreading, through which sulphide-laden fluids escape.
Blaster - A mine employee responsible for loading, priming and detonating blastholes.
Blast furnace - A reaction vessel in which mixed charges of oxide ores, fluxes and fuels are blown with a continuous blast of hot air and oxygen-enriched air for the chemical reduction of metals to their metallic state.
Blasthole - A drill hole in a mine that is filled with explosives in order to blast loose a quantity of rock.
Blister copper - A crude form of copper (assaying about 99%) produced in a smelter, which requires further refining before being used for industrial purposes.
Block caving - An inexpensive method of mining in which large blocks of ore are undercut, causing the ore to break or cave under its own weight.
Board lot - One hundred shares.
Bond - An agreement to pay a certain amount of interest over a given period of time.
Boom - A telescoping, hydraulically powered steel arm on which drifters, manbaskets and hydraulic hammers are mounted.
Box hole - A short raise or opening driven above a drift for the purpose of drawing ore from a stope, or to permit access.
Break - Loosely used to describe a large-scale regional shear zone or structural fault.
Breast - A working face in a mine, usually restricted to a stope.
Breccia - A rock in which angular fragments are surrounded by a mass of fine-grained minerals.
Broken reserves - The ore in a mine which has been broken by blasting but which has not yet been transported to surface.
Brunton compass - A pocket compass equipped with sights and a reflector, used for sighting lines, measuring dip and carrying out preliminary surveys.
Bulk mining - Any large-scale, mechanized method of mining involving many thousands of tonnes of ore being brought to surface per day.
Bulk sample - A large sample of mineralized rock, frequently hundreds of tonnes, selected in such a manner as to be representative of the potential orebody being sampled. Used to determine metallurgical characteristics.
Bullion - Metal formed into bars or ingots.
Bull market - Term used to describe financial market conditions when share prices are going up.
Bull quartz - A prospector's term for white, coarse-grained, barren quartz.
Byproduct - A secondary metal or mineral product recovered in the milling process.
C
Cable bolt - A steel cable, capable of withstanding tens of tonnes, cemented into a drillhole to lend support in blocky ground.
Cage - The conveyance used to transport men and equipment between the surface and the mine levels.
Calcine - Name given to concentrate that is ready for smelting (i.e. the sulphur has been driven off by oxidation).
Call - An option to buy shares at a specified price. The opposite of a "put".
Capitalization - A financial term used to describe the value financial markets put on a company. Determined by multiplying the number of outstanding shares of a company by the current stock price.
Capital stock - The total ownership of a limited liability company divided among a specified number of shares.
Captive stope - A stope that is accessible only through a manway.
Carbon-in-pulp - A method of recovering gold and silver from pregnant cyanide solutions by adsorbing the precious metals to granules of activated carbon, which are typically ground up coconut shells.
Cash flow - The net of the inflow and outflow of cash during an accounting period. Does not account for depreciation or bookkeeping write-offs which do not involve an actual cash outlay.
Cathode - A rectangular plate of metal, produced by electrolytic refining, which is melted into commercial shapes such as wirebars, billets, ingots, etc.
Cesium magnetometer - An geophysical instrument which measures magnetic field strength in terms of vertical gradient and total field.
Chalcocite - A sulphide mineral of copper common in the zone of secondary enrichment.
Chalcopyrite - A sulphide mineral of copper and iron; the most important ore mineral of copper.
Change house - The mine building where workers change into work clothes; also known as the "dry".
Channel sample - A sample composed of pieces of vein or mineral deposit that have been cut out of a small trench or channel, usually about 10 cm wide and 2 cm deep.
Charter - A document issued by a governing authority creating a company or other corporation.
Chartered bank - A financial institution that accepts deposits and provides loans.
Chip sample - A method of sampling a rock exposure whereby a regular series of small chips of rock is broken off along a line across the face.
Chromite - The chief ore mineral of chromium.
Chute - An opening, usually constructed of timber and equipped with a gate, through which ore is drawn from a stope into mine cars.
Cinnabar - A vermilion-colored ore mineral of mercury.
Circulating load - Over-sized chunks of ore returned to the head of a closed grinding circuit before going on to the next stage of treatment.
Claim - A portion of land held either by a prospector or a mining company. In Canada, the common size is 1,320 ft. (about 400 m) square, or 40 acres (about 16 ha).
Clarification - Process of clearing dirty water by removing suspended material.
Classifier - A mineral-processing machine which separates minerals according to size and density.
Clay - A fine-grained material composed of hydrous aluminum silicates.
Cleavage - The tendency of a mineral to split along crystallographic planes.
Closed circuit - A loop in the milling process wherein a selected portion of the product of a machine is returned to the head of the machine for finishing to required specification.
Coal - A carbonaceous rock mined for use as a fuel.
Coalification - The metamorphic processes of forming coal.
Collar - The term applied to the timbering or concrete around the mouth of a shaft; also used to describe the top of a mill hole.
Column flotation - A milling process, carried out in a tall cylindrical column, whereby valuable minerals are separated from gangue minerals based on their wetability properties.
Common stock - Shares in a company which have full voting rights which the holders use to control the company in common with each other. There is no fixed or assured dividend as with preferred shares, which have first claim on the distribution of a company's earnings or assets.
Complex ore - An ore containing a number of minerals of economic value. The term often implies that there are metallurgical difficulties in liberating and separating the valuable metals.
Cone crusher - A machine which crushes ore between a gyrating cone or crushing head and an inverted, truncated cone known as a bowl.
Concentrate - A fine, powdery product of the milling process containing a high percentage of valuable metal.
Concentrator - A milling plant that produces a concentrate of the valuable minerals or metals. Further treatment is required to recover the pure metal.
Confirmation - A form delivered by a broker to the client, setting forth the details of stock sales or purchases for the client.
Conglomerate - A sedimentary rock consisting of rounded, water-worn pebbles or boulders cemented into a solid mass.
Contact - A geological term used to describe the line or plane along which two different rock formations meet.
Contact metamorphism - Metamorphism of country rocks adjacent to an intrusion, caused by heat from the intrusion.
Contango - A situation in which the price of a metal for forward or future delivery stands at a premium over the cash or spot price of the metal.
Continuous miner - A piece of mining equipment which produces a continuous flow of ore from the working face.
Controlled blasting - Blasting patterns and sequences designed to achieve a particular objective. Cast blasting, where the muck pile is cast in a particular direction, and deck blasting, where holes are loaded once but blasted in successive blasts days apart, are examples.
Converter - In copper smelting, a furnace used to separate copper metal from matte.
Core - The long cylindrical piece of rock, about an inch in diameter, brought to surface by diamond drilling.
Core barrel - That part of a string of tools in a diamond drill hole in which the core specimen is collected.
Cordillera - The continuous chain of mountain ranges on the western margin of North and South America.
Country rock - Loosely used to describe the general mass of rock adjacent to an orebody. Also known as the host rock.
Crosscut - A horizontal opening driven from a shaft and (or near) right angles to the strike of a vein or other orebody.
Crust - The outermost layer of the Earth; includes both continental and oceanic crust.
Cum-dividend - Buyer entitled to pending dividend payment.
Current assets - Assets of company which can and are likely to be converted into cash within a year. Includes cash, marketable securities, accounts receivable and supplies.
Current liabilities - A company's debts that are payable within a year's time.
Custom smelter - A smelter which processes concentrates from independent mines. Concentrates may be purchased or the smelter may be contracted to do the processing for the independent company.
Cut-and-fill - A method of stoping in which ore is removed in slices, or lifts, and then the excavation is filled with rock or other waste material (backfill), before the subsequent slice is extracted.
Cut value - Applies to assays that have been reduced to some arbitrary maximum to prevent erratic high values from inflating the average.
Cyanidation - A method of extracting exposed gold or silver grains from crushed or ground ore by dissolving it in a weak cyanide solution. May be carried out in tanks inside a mill or in heaps of ore out of doors.
Cyanide - A chemical species containing carbon and nitrogen used to dissolve gold and silver from ore.
D
Day order - An order to buy or sell shares, good only on the day the order was entered.
Debenture - See bonds.
Debt financing - Method of raising capital whereby companies borrow money from a lending institution.
Deck - The area around the shaft collar where men and materials enter the cage to be lowered underground.
Decline - A sloping underground opening for machine access from level to level or from surface; also called a ramp.
Deferred charges - Expenses incurred but not charged against the current year's operation.
Depletion - An accounting device, used primarily in tax computations. It recognizes the consumption of an ore deposit, a mine's principal asset.
Depreciation - The periodic, systematic charging to expense of plant assets reflecting the decline in economic potential of the assets.
Development - Underground work carried out for the purpose of opening up a mineral deposit. Includes shaft sinking, crosscutting, drifting and raising.
Development drilling - drilling to establish accurate estimates of mineral reserves.
Diabase - A common basic igneous rock usually occurring in dykes or sills.
Diamond - The hardest known mineral, composed of pure carbon; low-quality diamonds are used to make bits for diamond drilling in rock.
Diamond drill - A rotary type of rock drill that cuts a core of rock that is recovered in long cylindrical sections, two cm or more in diameter.
Diamond driller - A person who operates a diamond drill.
Dilution (mining) - Rock that is , by necessity, removed along with the ore in the mining process, subsequently lowering the grade of the ore.
Dilution (of shares) - A decrease in the value of a company's shares caused by the issue of treasury shares.
Diorite - An intrusive igneous rock composed chiefly of sodic plagioclase, hornblende, biotite or pyroxene.
Dip - The angle at which a vein, structure or rock bed is inclined from the horizontal as measured at right angles to the strike.
Dip needle - A compass with the needle mounted so as to swing in a vertical plane, used for prospecting to determine the magnetic attraction of rocks.
Directional drilling - A method of drilling involving the use of stabilizers and wedges to direct the orientation of the hole.
Discount - The minimum price below the par value at which treasury shares may legally be sold.
Disseminated ore - Ore carrying small particles of valuable minerals spread more or less uniformly through the host rock.
Dividend - Cash or stock awarded to preferred and common shareholders at the discretion of the company's board of directors.
Dividend claim - Made when a dividend has been paid to the previous holder because stock has not yet been transferred to the name of the new owner.
Dor bar - The final saleable product of a gold mine. Usually consisting of gold and silver.
Drag fold - The result of the plastic deformation of a rock unit where it has been folded or bent back on itself.
Drawpoint - An underground opening at the bottom of a stope through which broken ore from the stope is extracted.
Drift - A horizontal underground opening that follows along the length of a vein or rock formation as opposed to a crosscut which crosses the rock formation.
Drifter - A hydraulic rock drill used to drill small-diameter holes for blasting or for installing rock bolts.
Drill-indicated reserves - The size and quality of a potential orebody as suggested by widely spaced drillholes; more work is required before reserves can be classified as probable or proven.
Dry - A building where the miner changes into working clothes.
Due diligence - The degree of care and caution required before making a decision; loosely, a financial and technical investigation to determine whether an investment is sound.
Dump - A pile of broken rock or ore on surface.
Dyke - A long and relatively thin body of igneous rock that, while in the molten state, intruded a fissure in older rocks.
E
Electrolysis - An electric current is passed through a solution containing dissolved metals, causing the metals to be deposited onto a cathode.
Electrolytic refining - The process of purifying metal ingots that are suspended as anodes in an electrolytic bath, alternated with refined sheets of the same metal which act as starters or cathodes.
EM survey - A geophysical survey method which measures the electromagnetic properties of rocks.
En echelon - Roughly parallel but staggered structures.
Environmental impact study - A written report, compiled prior to a production decision, that examines the effects proposed mining activities will have on the natural surroundings.
Epigenetic - Orebodies formed by hydrothermal fluids and gases that were introduced into the host rocks from elsewhere, filling cavities in the host rock.
Epithermal deposit - A mineral deposit consisting of veins and replacement bodies, usually in volcanic or sedimentary rocks, containing precious metals or, more rarely, base metals.
Equity financing - The provision of funds by buying shares.
Era - A large division of geologic time - the Precambrian era, for example.
Erosion - The breaking down and subsequent removal of either rock or surface material by wind, rain, wave action, freezing and thawing and other processes.
Erratic - Either a piece of visible gold or a large glacial boulder.
Escrowed shares - Shares deposited in trust pending fulfilment of certain conditions, and not ordinarily available to trading until released.
Ex-dividend - On stocks selling "ex-dividend", the seller retains the right to a pending dividend payment.
Exploration - Prospecting, sampling, mapping, diamond drilling and other work involved in searching for ore.
F
Face - The end of a drift, crosscut or stope in which work is taking place.
Fault - A break in the Earth's crust caused by tectonic forces which have moved the rock on one side with respect to the other.
Feldspar - A group of common rock-forming minerals that includes microcline, orthoclase, plagioclase and others.
Felsic - Term used to describe light-colored rocks containing feldspar, feldspathoids and silica.
Ferrous - Containing iron.
Fine gold - Fineness is the proportion of pure gold or silver in jewelry or bullion expressed in parts per thousand. Thus, 925 fine gold indicates 925 parts out of 1,000, or 92.5% is pure gold.
Fissure - An extensive crack, break or fracture in rocks.
Fixed Assets - Possessions such as buildings, machinery and land which, as opposed to current assets, are unlikely to be converted into cash during the normal business cycle.
Float - Pieces of rock that have been broken off and moved from their original location by natural forces such as frost or glacial action.
Flotation - A milling process in which valuable mineral particles are induced to become attached to bubbles and float as others sink.
Flowsheet - An illustration showing the sequence of operations, step by step, by which ore is treated in a milling, concentration or smelting process.
Flow-through shares - Shares in an exploration company that allow the tax deduction or credits for mineral exploration to be passed to the investor.
Flux - A chemical substance that reacts with gangue minerals to form slags, which are liquid at furnace temperature and low enough in density to float on the molten bath of metal or matte.
Fluxgate magnetometer - An instrument used in geophysics to measure total magnetic field.
Fold - Any bending or wrinkling of rock strata.
Footwall - The rock on the underside of a vein or ore structure.
Forward contract - The sale or purchase of a commodity for delivery at a specified future date.
Fracture - A break in the rock, the opening of which allows mineral-bearing solutions to enter. A "cross-fracture" is a minor break extending at more-or-less right angles to the direction of the principal fractures.
Free milling - Ores of gold or silver from which the precious metals can be recovered by concentrating methods without resorting to pressure leaching or other chemical treatment.
G
Gabbro - A dark, coarse-grained igneous rock.
Galena - Lead sulphide, the most common ore mineral of lead.
Gamma - A unit of measurement of magnetic intensity.
Gangue - The worthless minerals in an ore deposit.
Geiger counter - An instrument used to measure the radioactivity that emanates from certain minerals by means of a Geiger-Mueller tube.
Geochemistry - The study of the chemical properties of rocks.
Geology - The science concerned with the study of the rocks which compose the Earth.
Geophysics - The study of the physical properties of rocks and minerals.
Geophysical survey - A scientific method of prospecting that measures the physical properties of rock formations. Common properties investigated include magnetism, specific gravity, electrical conductivity and radioactivity.
Geothermal - Pertains to the heat of the Earth's interior.
Glacial drift - Sedimentary material that has been transported by glaciers.
Glacial striations - Lines or scratches on a smooth rock surface caused by glacial abrasion.
Glory hole - An open pit from which ore is extracted, especially where broken ore is passed to underground workings before being hoisted.
Gneiss - A layered or banded crystalline metamorphic rock, the grains of which are aligned or elongated into a roughly parallel arrangement.
Gold loan - A form of debt financing whereby a potential gold producer borrows gold from a lending institution, sells the gold on the open market, uses the cash for mine development, then pays back the gold from actual mine production.
Gossan - The rust-colored capping or staining of a mineral deposit, generally formed by the oxidation or alteration of iron sulphides.
Gouge - Fine, putty-like material composed of ground-up rock found along a fault.
Grab sample - A sample from a rock outcrop that is assayed to determine if valuable elements are contained in the rock. A grab sample is not intended to be representative of the deposit, and usually the best-looking material is selected.
Graben - A downfaulted block of rock.
Granite - A coarse-grained intrusive igneous rock consisting of quartz, feldspar and mica.
Gravity meter, gravimeter - An instrument for measuring the gravitational attraction of the earth; gravitational attraction varies with the density of the rocks in the vicinity.
Greenstone belt - An area underlain by metamorphosed volcanic and sedimentary rocks, usually in a continental shield.
Grizzly (or mantle) - A grating, usually constructed of steel rails, placed over the top of a chute or ore pass for the purpose of stopping large pieces of rock or ore that may hang up in the pass.
Gross value - The theoretical value of ore determined simply by applying the assay of metal or metals and the current market price. It must be used only with caution and severe qualification.
Gross value royalty - A share of gross revenue from the sale of minerals from a mine.
Grouting - The process of sealing off a water flow in rocks by forcing a thin slurry of cement or other chemicals into the crevices; usually done through a diamond drill hole.
Grubstake - Finances or supplies of food, etc., furnished to a prospector in return for an interest in any discoveries made.
Guides - The timber rails installed along the walls of a shaft for steadying, or guiding, the cage or conveyance.
Gypsum - A sedimentary rock consisting of hydrated calcium sulphate.
Gyratory crusher - A machine that crushes ore between an eccentrically mounted crushing cone and a fixed crushing throat. Typically has a higher capacity than a jaw crusher.
H
Halite - Rock salt.
Hangingwall - The rock on the upper side of a vein or ore deposit.
Head grade - The average grade of ore fed into a mill.
Heap leaching - A process whereby valuable metals, usually gold and silver, are leached from a heap, or pad, of crushed ore by leaching solutions percolating down through the heap and collected from a sloping, impermeable liner below the pad.
Hedging - Taking a buy or sell position in a futures market opposite to a position held in the cash market to minimize the risk of financial loss from an adverse price change.
Hematite - An oxide of iron, and one of that metal's most common ore minerals.
High grade - Rich ore. As a verb, it refers to selective mining of the best ore in a deposit.
High-grader - One who steals rich ore, especially gold, from a mine.
Hoist - The machine used for raising and lowering the cage or other conveyance in a shaft.
Holding company - A corporation engaged principally in holding a controlling interest in one or more other companies.
Hornfels - A fine-grained contact metamorphic rock.
Horse - A mass of waste rock lying within a vein or orebody.
Horst - An upfaulted block of rock.
Host rock - The rock surrounding an ore deposit.
Hydrometallurgy - The treatment of ore by wet processes, such as leaching, resulting in the solution of a metal and its subsequent recovery.
Hydrothermal - Relating to hot fluids circulating in the earth's crust.
I
Igneous rocks - Rocks formed by the solidification of molten material from far below the earth's surface.
Ilmenite - An ore mineral of titanium, being an iron-titanium oxide.
Induced polarization - A method of ground geophysical surveying employing an electrical current to determine indications of mineralization.
Industrial minerals - Non-metallic, non-fuel minerals used in the chemical and manufacturing industries. Examples are asbestos, gypsum, salt, graphite, mica, gravel, building stone and talc.
Initial public offering - The first sale of shares to the public, usually by subscription from a group of investment dealers.
Institutional investors - Pension funds and mutual funds, managing money for a large number of individual investors.
Intermediate rock - An igneous rock containing 52% to 66% quartz.
Intrusive - A body of igneous rock formed by the consolidation of magma intruded into other rocks, in contrast to lavas, which are extruded upon the surface.
Ion exchange - An exchange of ions in a crystal with irons in a solution. Used as a method for recovering valuable metals, such as uranium, from solution.
J
Jaw crusher - A machine in which rock is broken by the action of steel plates.
Jig - A piece of milling equipment used to concentrate ore on a screen submerged in water, either by the reciprocating motion of the screen or by the pulsation of water through it.
K
Kimberlite - A variety of peridotite; the most common host rock of diamonds.
L
Lagging - Planks or small timbers placed between steel ribs along the roof of a stope or drift to prevent rocks from falling, rather than to support the main weight of the overlying rocks.
Lamprophyre - An igneous rock, composed of dark minerals, that occurs in dykes; sometimes contains diamonds.
Laterite - A residual soil, ususally found in tropical countries, out of which the silica has been leached. May form orebodies of iron, nickel, bauxite and manganese.
Launder - A chute or trough for conveying pulp, water or powdered ore in a mill.
Lava - A general name for the molten rock ejected by volcanoes.
Leachable - Extractable by chemical solvents.
Leaching - A chemical process for the extraction of valuable minerals from ore; also, a natural process by which ground waters dissolve minerals, thus leaving the rock with a smaller proportion of some of the minerals than it contained originally.
Lens - Generally used to describe a body of ore that is thick in the middle and tapers towards the ends.
Lenticular - A deposit having roughly the form of a double convex lens.
Level - The horizontal openings on a working horizon in a mine; it is customary to work mines from a shaft, establishing levels at regular intervals, generally about 50 metres or more apart.
Lignite - A soft, low-rank, brownish-black coal.
Limestone - A bedded, sedimentary deposit consisting chiefly of calcium carbonate.
Limit order - An order made by a client to a broker to buy or sell shares at a specified price or better.
Limonite - A brown, hydrous iron oxide.
Line cutting - Straight clearings through the bush to permit sightings for geophysical and other surveys.
Lode - A mineral deposit in solid rock.
Logging - The process of recording geological observations of drill core either on paper or on computer disk.
London fix - The twice-daily bidding session held by five dealing companies to set the gold price. There are also daily London fixes to set the prices of other precious metals.
London Metals Exchange - A major bidding market for base metals, which operates daily in London.
Long position - Securities owned outright or carried on margin.
Long ton - 2,240 lbs. avoirdupois (compared with a short ton, which is 2,000 lbs.).
M
Mafic - Igneous rocks composed mostly of dark, iron- and magnesium-rich minerals.
Magma - The molten material deep in the Earth from which rocks are formed.
Magmatic segregation - An ore-forming process whereby valuable minerals are concentrated by settling out of a cooling magma.
Magnetic gradient survey - A geophysical survey using a pair of magnetometers a fixed distance apart, to measure the difference in the magnetic field with height above the ground.
Magnetic separation - A process in which a magnetically susceptible mineral is separated from gangue minerals by applying a strong magnetic field; ores of iron are commonly treated in this way.
Magnetic susceptibility - A measure of the degree to which a rock is attracted to a magnet.
Magnetic survey - A geophysical survey that measures the intensity of the Earth's magnetic field.
Magnetite - Black, magnetic iron ore, an iron oxide.
Magnetometer - An instrument used to measure the magnetic attraction of underlying rocks.
Map-staking - A form of claim-staking practised in some jurisdictions whereby claims are staked by drawing lines around the claim on claim maps at a government office.
Marble - A metamorphic rock derived from the recrystallization of limestone under intense heat and pressure.
Margin - Cash deposited with a broker as partial payment of the purchase price for any type of listed stock. The stock is held by the broker as security for the loan.
Marginal deposit - An orebody of minimal profitability.
Market order - An order to buy or sell at the best price available. In absence of any specified price or limit, an order is considered to be "at the market".
Matte - A product of a smelter, containing metal and some sulphur, which must be refined further to obtain pure metal.
Metallurgical coal - Coal used to make steel.
Metallurgy - The study of extracting metals from their ores.
Metamorphic rocks - Rocks which have undergone a change in texture or composition as the result of heat and/or pressure.
Metamorphism - The process by which the form or structure of rocks is changed by heat and pressure.
Migmatite - Rock consisting of thin, alternating layers of granite and schist.
Mill - A plant in which ore is treated and metals are recovered or prepared for smelting; also a revolving drum used for the grinding of ores in preparation for treatment.
Milling ore - Ore that contains sufficient valuable mineral to be treated by milling process.
Millivolts - A measure of the voltage of an electric current, specifically, one-thousandth of a volt.
Minable reserves - Ore reserves that are known to be extractable using a given mining plan.
Mineral - A naturally occurring homogeneous substance having definite physical properties and chemical composition and, if formed under favorable conditions, a definite crystal form.
Muck - Ore or rock that has been broken by blasting.
Muck sample - A representative piece of ore that is taken from a muck pile and then assayed to determine the grade of the pile.
N
Nanotesla - The international unit for measuring magnetic flux density.
Native metal - A metal occurring in nature in pure form, uncombined with other elements.
Net profit interest - A portion of the profit remaining after all charges, including taxes and bookkeeping charges, such as depreciation, have been deducted.
Net smelter return - A share of the net revenues generated from the sale of metal produced by a mine.
Net worth - The difference between total assets and total liabilities.
Norite - A coarse-grained igneous rock that is host to copper/nickel deposits in the Sudbury area of Ontario.
Nugget - A small mass of precious metal, found free in nature.
O
Odd lot - A block of shares that is less than a board lot.
Open order - An order to buy or sell stock, which is good until cancelled by the client.
Open pit - A mine that is entirely on surface. Also referred to as open-cut or open-cast mine.
Option - An agreement to purchase a property reached between the property vendor and some other party who wishes to explore the property further.
Option (on stock) - The right to buy or sell a share at a set price, regardless of market value.
Ore - A mixture of ore minerals and gangue from which at least one of the metals can be extracted at a profit.
Ore pass - Vertical or inclined passage for the downward transfer of ore connecting a level with the hoisting shaft or a lower level.
Orebody - A natural concentration of valuable material that can be extracted and sold at a profit.
Ore Reserves - The calculated tonnage and grade of mineralization which can be extracted profitably; classified as possible, probable and proven according to the level of confidence that can be placed in the data.
Oreshoot - The portion, or length, of a vein or other structure that carries sufficient valuable minerals to be extracted profitably.
Organic maturation - The process of turning peat into coal.
Orogeny - A period of mountain-building characterized by the folding of a portion of the earth's crust.
Outcrop - An exposure of rock or mineral deposit that can be seen on surface, that is, not covered by soil or water.
Overturned - Where the oldest sedimentary rock beds are lying on top of a younger beds.
Oxidation - A chemical reaction caused by exposure to oxygen that results in a change in the chemical composition of a mineral.
P
Pan - To wash gravel, sand or crushed rock samples in order to isolate gold or other valuable metals by their higher density.
Participating interest - A company's interest in a mine, which entitles it to a certain percentage of profits in return for putting up an equal percentage of the capital cost of the project.
Par value - The stated face value of a stock. Par value shares have no specified face value, but the total amount of authorized capital is set down in the company's charter.
Patent - The ultimate stage of holding a mineral claim, after which no more assessment work is necessary because all mineral rights have been earned.
Pegmatite - A coarse-grained, igneous rock, generally coarse, but irregular in texture, and similar to a granite in composition; usually occurs in dykes or veins and sometimes contains valuable minerals.
Pellet - A marble-sized ball of iron ore fused with clay for transportation and use in steelmaking.
Pentlandite - Nickel iron sulphide, the most common nickel ore.
Peridotite - An intrusive igneous rock consisting mainly of olivine.
Phaneritic - A term used to describe the coarse-grained texture of some igneous rocks.
Picket line - A reference line, marked by pickets or stakes, established on a property for mapping and survey purposes.
Pig iron - Crude iron from a blast furnace.
Pillar - A block of solid ore or other rock left in place to structurally support the shaft, walls or roof of a mine.
Pitchblende - An important uranium ore mineral. It is black in color, possesses a characteristic greasy lustre and is highly radioactive.
Placer - A deposit of sand and gravel containing valuable metals such as gold, tin or diamonds.
Plant - A building or group of buildings in which a process or function is carried out; at a mine site it will include warehouses, hoisting equipment, compressors, maintenance shops, offices and the mill or concentrator.
Plate tectonics - A geological theory which postulates that the Earth's crust is made up of a number of rigid plates which collide, rub up against and spread out from one another.
Plug - A common name for a small offshoot from a large body of molten rock.
Plunge - The vertical angle a linear geological feature makes with the horizontal plane.
Plutonic - Refers to rocks of igneous origin that have come from great depth.
Point - Unit of value of a stock as quoted by a stock exchange. May represent one dollar, one cent or one-eighth of a dollar, depending on the stock exchange.
Polishing pond - The last in a series of settling ponds through which mill effluent flows before being discharged into the natural environment.
Pooling shares - See escrowed shares.
Porphyry - Any igneous rock in which relatively large crystals , called phenocrysts, are set in a fine-grained groundmass.
Porphyry copper - A deposit of disseminated copper minerals in or around a large body of intrusive rock.
Portal - The surface entrance to a tunnel or adit.
Portfolio - A list of financial assets.
Possible reserves - Valuable mineralization not sampled enough to accurately estimate its tonnage and grade, or even verify its existence. Also called "inferred reserves."
Potash - Potassium compounds mined for fertilizer and for use in the chemical industry.
Precambrian Shield - The oldest, most stable regions of the earth's crust, the largest of which is the Canadian Shield.
Preferred shares - Shares of a limited liability company that rank ahead of common shares, but after bonds, in distribution of earnings or in claim to the company's assets in the event of liquidation. They pay a fixed dividend but normally do not have voting rights, as with common shares.
Price-to-earnings ratio - The current market price of a stock divided by the company's net earnings per share for the year.
Primary deposits - Valuable minerals deposited during the original period or periods of mineralization, as opposed to those deposited as a result of alteration or weathering.
Private placement - Sale of shares to individuals or corporations outside the normal market, at a negotiated price. Often used to raise capital for a junior exploration company.
Pro rata - In proportion, usually to ownership, income or contribution.
Probable reserves - Valuable mineralization not sampled enough to accurately estimate the terms of tonnage and grade. Also called "indicated reserves."
Profit and loss statement - The income statement of a company detailing revenues minus total costs to give total profit.
Prospect - A mining property, the value of which has not been determined by exploration.
Prospectus - A document filed with the appropriate securities commission detailing the activities and financial condition of a company seeking funds from the public through the issuance of shares.
Proton precession magnetometer - A geophysical instrument which measures magnetic field intensity in terms of vertical gradient and total field.
Proven reserves - Reserves that have been sampled extensively by closely spaced diamond drill holes and developed by underground workings in sufficient detail to render an accurate estimation of grade and tonnage. Also called "measured reserves."
Proxy - A power of attorney given by the shareholder so that his stock may be voted by his nominee(s) at shareholders' meetings.
Pulp - Pulverized or ground ore in solution.
Put - An option to sell a stock at an agreed upon price within a specified time. The owner can present his put to the contracting broker at any time within the option period and compel him to buy the stock.
Pyramiding - The use of increased buying power to increase ownership arising from price appreciation.
Pyrite - A yellow iron sulphide mineral, normally of little value. It is sometimes referred to as "fool's gold".
Pyrrhotite - A bronze-colored, magnetic iron sulphide mineral.
Q
Quartz - Common rock-forming mineral consisting of silicon and oxygen.
Quartzite - A metamorphic rock formed by the transformation of a sandstone by heat and pressure.
R
Radioactivity - The property of spontaneously emitting alpha, beta or gamma rays by the decay of the nuclei of atoms.
Radon survey - A geochemical survey technique which detects traces of radon gas, a product of radioactivity.
Raise - A vertical or inclined underground working that has been excavated from the bottom upward.
Rake - The trend of an orebody along the direction of its strike.
Rare earth elements - Relatively scarce minerals such as niobium and yttrium.
Reaming shell - A component of a string of rods used in diamond drilling, it is set with diamonds and placed between the bit and the core barrel to maintain the gauge (or diameter) of the hole.
Reclamation - The restoration of a site after mining or exploration activity is completed.
Reconnaissance - A preliminary survey of ground.
Record date - The date by which a shareholder must be registered on the books of a company in order to receive a declared dividend, or to vote on company affairs.
Recovery - The percentage of valuable metal in the ore that is recovered by metallurgical treatment.
Refractory ore - Ore that resists the action of chemical reagents in the normal treatment processes and which may require pressure leaching or other means to effect the full recovery of the valuable minerals.
Regional metamorphism - Metamorphism caused by both the heat of igneous processes and tectonic pressure.
Replacement ore - Ore formed by a process during which certain minerals have passed into solution and have been carried away, while valuable minerals from the solution have been deposited in the place of those removed.
Resistivity survey - A geophysical technique used to measure the resistance of a rock formation to an electric current.
Resource - The calculated amount of material in a mineral deposit, based on limited drill information.
Resuing - A method of stoping in narrow-vein deposits whereby the wallrock on one side of the vein is blasted first and then the ore.
Reverberatory furnace - A long, flat furnace used to slag gangue minerals and produce a matte.
Rhyolite - A fine-grained, extrusive igneous rock which has the same chemical composition as granite.
Rib samples - Ore taken from rib pillars in a mine to determine metal content.
Rights - In finance, a certified right to purchase treasury shares in stated quantities, prices and time limits; usually negotiable at a price which is related to the prices of the issue represented; also referred to as warrants. Rights and warrants can be bought and sold prior to their expiry date because not all shareholders wish to exercise their rights.
Rock - Any natural combination of minerals; part of the earth's crust.
Rockbolting - The act of supporting openings in rock with steel bolts anchored in holes drilled especially for this purpose.
Rockburst - A violent release of energy resulting in the sudden failure of walls or pillars in a mine, caused by the weight or pressure of the surrounding rocks.
Rock factor - The number of cubic metres of a particular rock type required to make up one tonne of the material. One tonne of a highly siliceous ore may occupy 0.40 cubic metres, while a tonne of dense sulphide ore may occupy only 0.25 cubic metres.
Rock mechanics - The study of the mechanical properties of rocks, which includes stress conditions around mine openings and the ability of rocks and underground structures to withstand these stresses.
Rod mill - A rotating steel cylinder that uses steel rods as a means of grinding ore.
Room-and-pillar mining - A method of mining flat-lying ore deposits in which the mined-out area, or rooms, are separated by pillars of approximately the same size.
Rotary drill - A machine that drills holes by rotating a rigid, tubular string of drill rods to which is attached a bit. Commonly used for drilling large-diameter blastholes in open-pit mines.
Royalty - An amount of money paid at regular intervals by the lessee or operator of an exploration or mining property to the owner of the ground. Generally based on a certain amount per tonne or a percentage of the total production or profits. Also, the fee paid for the right to use a patented process.
Run-of-mine - A term used loosely to describe ore of average grade.
S
Salting - The act of introducing metals or minerals into a deposit or samples, resulting in false assays. Done either by accident or with the intent of defrauding the public.
Sample - A small portion of rock or a mineral deposit taken so that the metal content can be determined by assaying.
Sampling - Selecting a fractional but representative part of a mineral deposit for analysis.
Sandstone - A sedimentary rock consisting of grains of sand cemented together.
Scaling - The act of removing loose slabs of rock from the back and walls of an underground opening, usually done with a hand-held scaling bar or with a boom-mounted scaling hammer.
Scarp - An escarpment, cliff or steep slope along the margin of a plateau, mesa or terrace.
Schist - A foliated metamorphic rock the grains of which have a roughly parallel arrangement; generally developed by shearing.
Scintillation counter - An instrument used to detect and measure radioactivity by detecting gamma rays; more sensitive than a geiger counter.
Secondary enrichment - Enrichment of a vein or mineral deposit by minerals that have been taken into solution from one part of the vein or adjacent rocks and redeposited in another.
Sedimentary rocks - Secondary rocks formed from material derived from other rocks and laid down under water. Examples are limestone, shale and sandstone.
Seismic prospecting - A geophysical method of prospecting, utilizing knowledge of the speed of reflected sound waves in rock.
Self-potential - A technique, used in geophysical prospecting, which recognizes and measures the minute electric currents generated by sulphide deposits.
Semi-autogenous grinding (SAG) - A method of grinding rock into fine powder whereby the grinding media consist of larger chunks of rocks and steel balls.
Serpentine - A greenish, metamorphic mineral consisting of magnesium silicate.
Shaft - A vertical or inclined excavation in rock for the purpose of providing access to an orebody. Usually equipped with a hoist at the top, which lowers and raises a conveyance for handling workers and materials.
Shale - Sedimentary rock formed by the consolidation of mud or silt.
Shear or shearing - The deformation of rocks by lateral movement along innumerable parallel planes, generally resulting from pressure and producing such metamorphic structures as cleavage and schistosity.
Shear zone - A zone in which shearing has occurred on a large scale.
Sheave wheel - A large, grooved wheel in the top of a headframe over which the hoisting rope passes.
Shoot - A concentration of mineral values; that part of a vein or zone carrying values of ore grade.
Short selling - The borrowing of stock from a broker in order to sell it in the hope that it may be purchased at a lower price later on.
Short ton - 2,000 lbs. avoirdupois.
Shrinkage stoping - A stoping method which uses part of the broken ore as a working platform and as support for the walls of the stope.
Siderite - Iron carbonate, which when pure, contains 48.2% iron; must be roasted to drive off carbon dioxide before it can be used in a blast furnace. Roasted product is called sinter.
Silica - Silicon dioxide. Quartz is a common example.
Siliceous - A rock containing an abundance of quartz.
Sill - An intrusive sheet of igneous rock of roughly uniform thickness that has been forced between the bedding planes of existing rock.
Silt - Muddy deposits of fine sediment usually found on the bottoms of lakes.
Sinter - Fine particles of iron ore that have been treated by heat to produce blast furnace feed.
Skarn - Name for the metamorphic rocks surrounding an igneous intrusive where it comes in contact with a limestone or dolostone formation.
Skip - A self-dumping bucket used in a shaft for hoisting ore or rock.
Slag - The vitreous mass separated from the fused metals in the smelting process.
Slash - The process of blasting rock from the side of an underground opening to widen the opening.
Slate - A metamorphic rock; the metamorphic equivalent of shale.
Slickenside - The striated, polished surface of a fault caused by one wall rubbing against the other.
Sludge - Rock cuttings from a diamond drill hole, sometimes used for assaying.
Sodium cyanide - A chemical used in the milling of gold ores to dissolve gold and silver.
Solvent extraction-electrowinning (SX-EW) - A metallurgical technique, so far applied only to copper ores, in which metal is dissolved from the rock by organic solvents and recovered from solution by electrolysis.
Spelter - The zinc of commerce, more or less impure, cast from molten metal into slabs or ingots.
Sphalerite - A zinc sulphide mineral; the most common ore mineral of zinc.
Split - The shareholder-approved division of a company's outstanding common shares into a larger number of new common shares.
Spot price - Current delivery price of a commodity traded in the spot market.
Station - An enlargement of a shaft made for the storage and handling of equipment and for driving drifts at that elevation.
Step-out drilling - Holes drilled to intersect a mineralization horizon or structure along strike or down dip.
Stock exchange - An organized market concerned with the buying and selling of common and preferred shares and warrants by stockbrokers who own seats on the exchange and meet membership requirements.
Stockpile - Broken ore heaped on surface, pending treatment or shipment.
Stope - An excavation in a mine from which ore is, or has been, extracted.
Stop-loss order - An arrangement whereby a client gives his broker instructions to sell a stock if and when its price drops to a specified figure on the market.
Stratigraphy - Strictly, the description of bedded rock sequences; used loosely, the sequence of bedded rocks in a particular area.
Streak - A diagnostic characteristic of minerals, where scratching a sample on a piece of unglazed porcelain leaves powder of a characteristic color.
Street certificate - A certificate representing ownership in a specified number of shares that is registered in the name of some previous owner who has endorsed the certificate so that it may be transferred to a new owner without referral to transfer agent.
Striations - Prominent parallel scratches left on bedrock by advancing glaciers.
Strike - The direction, or bearing from true north, of a vein or rock formation measure on a horizontal surface.
Stringer - A narrow vein or irregular filament of a mineral or minerals traversing a rock mass.
Strip - To remove the overburden or waste rock overlying an orebody in preparation for mining by open pit methods.
Stripping ratio - The ratio of tonnes removed as waste relative to the number of tonnes of ore removed from an open-pit mine.
Strip mine - An open-pit mine, usually a coal mine, operated by removing overburden, excavating the coal seam, then returning the overburden.
Sub-bituminous - A black coal, intermediate between lignite and bituminous.
Sublevel - A level or working horizon in a mine between main working levels.
Subsidiary company - A company in which the majority of shares (a controlling position) is held by another company.
Sulphide - A compound of sulphur and some other element.
Sulphide dust explosions - An underground mining hazard involving the spontaneous combustion of airborne dust containing sulphide minerals.
Sulphur dioxide - A gas liberated during the smelting of most sulphide ores; either converted into sulphuric acid or released into the atmosphere in the form of a gas.
Sump - An underground excavation where water accumulates before being pumped to surface.
Sustainable development - Industrial development that does not detract from the potential of the natural environment to provide benefits to future generations.
Syenite - An intrusive igneous rock composed chiefly of orthoclase.
Sylvite - potassium chloride, the principal ore of potassium mined for fertilizer manufacturing.
Syncline - A down-arching fold in bedded rocks.
Syngenetic - A term used to describe when mineralization in a deposit was formed relative to the host rocks in which it is found. In this case, the mineralization was formed at the same time as the host rocks. (The opposite is epigenetic.)
T
Taconite - A highly abrasive iron ore.
Tailings - Material rejected from a mill after most of the recoverable valuable minerals have been extracted.
Tailings pond - A low-lying depression used to confine tailings, the prime function of which is to allow enough time for heavy metals to settle out or for cyanide to be destroyed before water is discharged into the local watershed.
Talus - A heap of broken, coarse rock found at the base of a cliff or mountain.
Telluride - A chemical compound consisting of the element tellurium and another element, often gold or silver.
Thermal coal - Coal burned to generate the steam that drives turbines to generate electricity.
Thickener - A large, round tank used in milling operations to separate solids from liquids; clear fluid overflows from the tank and rock particles sink to the bottom.
Tonnes-per-vertical-metre - Common unit used to describe the amount of ore in a deposit; ore length is multiplied by the width and divided by the appropriate rock factor to give the amount of ore for each vertical metre of depth.
Trading floor - the area of a stock exchange building where shares are bought and sold.
Trading post - An area on the trading floor of a stock exchange where current stock prices are listed and where the floor traders (representatives of brokerage firms) meet to buy or sell the stocks listed at that particular post.
Tram - To haul cars of ore or waste in a mine.
Treasury shares - The unissued shares in a company's treasury.
Trench - A long, narrow excavation dug through overburden, or blasted out of rock, to expose a vein or ore structure.
Trend - The direction, in the horizontal plane, of a linear geological feature, such as an ore zone, measured from true north.
Tube mill - An apparatus consisting of a revolving cylinder about half-filled with steel rods or balls and into which crushed ore is fed for fine grinding.
Tuff - Rock composed of fine volcanic ash.
Tunnel - A horizontal underground opening, open to the atmosphere at both ends.
Tunnel-boring-machine - A machine used to excavate a tunnel through soil or rock by mechanical means as opposed to drilling and blasting.
U
Umpire sample or assay - An assay made by a third party to provide a basis for settling disputes between buyers and sellers of ore.
Uncut value - The actual assay value of a core sample as opposed to a cut value which has been reduced by some arbitrary formula.
Underwrite - A firm commitment made by a broker or other financial institution to purchase a block of shares at a specified price.
Uraninite - A uranium mineral with a high uranium oxide content. Frequently found in pegmatite dykes.
Uranium - A radioactive, silvery-white, metallic element.
V
Vein - A fissure, fault or crack in a rock filled by minerals that have travelled upwards from some deep source.
Vendor - A seller. In the case of mining companies, the consideration paid for properties purchased is often a block of treasury shares. These shares are termed vendor shares and are normally pooled or escrowed.
Visible gold - Native gold which is discernible, in a hand specimen, to the unaided eye.
Volcanic rocks - Igneous rocks formed from magma that has flowed out or has been violently ejected from a volcano.
Volcanogenic - A term used to describe the volcanic origin of mineralization.
Voting right - The stockholder's right to vote in the affairs of the company. Most common shares have one vote each. Preferred stock usually has the right to vote when preferred dividends are in default.
Vug - A small cavity in a rock, frequently lined with well-formed crystals. Amethyst commonly forms in these cavities.
W
Wall rocks - Rock units on either side of an orebody. The hangingwall and footwall rocks of an orebody.
Warrant - See Rights.
Waste - Unmineralized, or sometimes mineralized, rock that is not minable at a profit.
Wedge - A technique of directing a diamond drill hole in a desired direction away from its current orientation.
Winze - An internal shaft.
Witness post - A claim post placed on a claim line when it cannot be placed in the corner of a claim because of water or difficult terrain.
Working capital - The liquid resources a company has to meet day-to-day expenses of operation; defined as the excess of current assets over current liabilities.
Writeoffs - Amounts deducted from a company's reported profit for depreciation or preproduction costs. Writeoffs are not an out-of-pocket expense, but reduce the amount of taxable profit.
X
Xenolith - A fragment of country rock enclosed in an intrusive rock.
Y
Yield - The current annual dividend rate expressed as a percentage of the current market price of the stock.
Z
Zone - An area of distinct mineralization.
Zone of oxidation - The upper portion of an orebody that has been oxidized.
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Post by likeike on Jul 17, 2023 13:58:43 GMT
GOLD RECOVERY 101 Gold recovery is a crucial part of the mining industry. Gold can be found in almost everything we see and touch; there are several important industrial uses for gold in electronics, dentistry, and aerospace; however, almost 80% of gold ends up being used for jewelry. While jewelry is the end of the road for most mined gold, there are many ways it occurs in nature. These different types of occurrences can impact the processes used for gold recovery.
In nature, gold occurs primarily as a native metal often alloyed with silver, copper, and mercury to varying extents. Native gold occurrences vary widely in particle size and mineral association. Gold deposits can be classified into two primary classes: placer, where the gold has already been liberated from the host rock by natural weathering, typically by water erosion; and hard rock (or lode), where the gold is still locked within the host rock.
Interested in gold recovery and gold recovery equipment? Sepro manufactures a range of high-quality mining equipment to help with your gold recovery project. Contact our experts if you need help finding the right mining equipment for your project!
TYPES OF GOLD DEPOSITS Placer Deposits Placer deposits contain gold that has been liberated and preconcentrated by natural weathering forces. Placer deposits typically consist of gravels, sands or laterites that can be mined easily without the need for blasting. The gold in placer deposits is often coarse, fully liberated and easily recovered by traditional gravity concentration techniques without any crushing or grinding.
Hard Rock Deposits Hard rock or lode deposits share a common trait: the gold is locked or occluded in the surrounding rock matrix where crushing and often grinding is required to liberate it. Hard rock gold deposits can be further classified into three sub classes: free milling, sulfide associated and refractory.
Free-Milling Gold Gold ore is considered free-milling when over 90% of the gold can be recovered by a conventional gravity-cyanidation process with low reagent consumptions at a grind size of 80% passing 75 µm. Some examples of free-milling gold ores include quartz-veined deposits and oxidized ores.
Sulfide-Associated Gold Gold often occurs in close association with sulfide minerals such as arsenopyrite, pyrite and chalcopyrite. Sulfide-associated gold is often very fine in nature and difficult to separate from the sulfides.
Refractory Gold A refractory gold ore can be defined as any ore that responds poorly to a conventional gravitycyanidation process with examples often including copper porphyry, complex sulfides, arsenopyrite and lead-zinc associations. There are several factors that can render an ore refractory. Ultra-fine disseminated gold particles can be trapped within the mineral matrix, even at fine grind sizes.
The ore can contain highly reactive minerals that consume free cyanide or oxygen. In addition, the ore can contain preg-robbing elements such as organic carbon that will re-adsorb the dissolved gold as it is leached. While the factors that make an ore refractory are varied, a common trait is requiring some sort of pre-treatment before being economically recovered by conventional cyanidation.
Finally, there are some minerals in which non-native gold occurs as a chemically bound solid solution with other elements. These relatively rare minerals include calaverite, sylvanite, maldonite and aurostibnite and make up a small fraction of global gold production.
GOLD RECOVERY METHODS Placer Deposits The most cost-effective solutions for gold recovery from placer deposits use the principles of gravity concentration. In the case of sand or gravel type placer deposits, the material is screened to remove large rocks or boulders; the screen undersize is processed using a sluice or jig. In the case of placer deposits with a high clay content, a scrubber or trommel screen is typically used to separate the gold bearing sands from the clays ahead of the gravity units. The use of a trommel screen can result in fine gold being lost with clay; industry best practice is to use a rotary scrubber followed by a horizontal vibrating screen for maximum washing and screening efficiency.
If a significant portion of gold is fine (<300 µm), a high G-Force centrifugal concentrator can be used to improve recovery.
Free-Milling Gold Low Grade In the case of low grade (< 1 g/t) free-milling gold deposits, the ore is often crushed and heap leached. While the recoveries are typically lower than what would be obtained with a conventional gravity cyanidation flowsheet, the savings in CAPEX and grinding costs often justify this route. When clays or fine particles are present, the use of an agglomeration drum is necessary to prevent impenetrable dead zones in the heap.
High Grade Free-milling gold ores contain gold particles that can be liberated by grinding and are economically recoverable using traditional processing technologies.
A typical flowsheet for a hard rock free-milling gold ore is presented on the next page in Figure 1:
Figure 1: Traditional free-milling gold process Blasted rocks from the mine are crushed to less than one inch (25 mm) before being fed to a ball or SAG mill. The discharge from the mill is pumped to a cyclone for classification. Hydrocyclones separate the particles based on their size and density with the fine, light particles reporting to the cyclone overflow (COF) and the coarser and denser particles reporting to the cyclone underflow (CUF) for further grinding.
Eventually, the ore is ground fine enough (typically in the range of 75-250 µm P80) and reports to the cyclone overflow. From there, the fine gold particles that have reported to the cyclone overflow, are extracted through a cyanide leaching and carbon adsorption process. A high-grade gold solution is then produced for electrowinning which is followed by smelting to create doré bars. Doré is a semi-pure alloy of gold and silver.
Gold by nature is very dense (19.3x denser than water and 7.3x denser than quartz) and malleable, causing it to grind slowly. These properties cause gold particles to preferentially report to the cyclone underflow and accumulate in the grinding circuit over time. In order to take advantage of gold’s preferential deportment to the cyclone underflow, the installation of a gravity concentrator to treat a portion (10-100%) of this stream can lead to a large benefit at a relatively low throughput and capital cost.
The high-grade concentrates from the primary gravity concentrator have traditionally been upgraded with a shaking table before being smelted and poured into doré bars. In recent years, intensive leaching of the gravity concentrate has become the preferred process option because of increased recoveries, improved security and lower safety concerns with modern equipment. The high-grade leach solution from the intensive leach reactor is electrowon and smelted similar to the gold from the primary leaching circuit.
Other benefits of installing a gravity concentrator within the grinding circuit include:
• Increase in overall recovery – A rule of thumb is for every 10% recovery by gravity, an increase of 1% in overall plant recovery can be expected
• Reduced grade variability – By recovering coarse-free gold in the grinding circuit, the feed grade to the downstream leach or flotation circuit will be much more consistent and less prone to upset resulting in much easier leaching or flotation circuit optimization.
• Reduction in leach circuit CAPEX – By recovering the coarse, slow-leaching gold particles in the gravity circuit, the retention time and thus the size of the leach circuit, can be significantly reduced (alternatively more tons can be processed by the same size leach circuit).
Note: In some cases, if the gravity recoveries are high enough, the leach circuit can be eliminated all together.
• Reduction in reagent consumption – By lowering the feed grade to the leach circuit, the amount of cyanide and other reagents required can be reduced by as much as 70%.
• Less gold inventory lock-up – Gold’s high density makes it likely to settle out and accumulate in pump boxes and behind mill liners; by removing the gold as soon as it is liberated the gold lockup is significantly reduced and security is improved.
Sulfide-Associated Gold Gold is often associated with many sulfide minerals including arsenopyrite, pyrite, chalcopyrite and galena. Often a portion of the sulfide-associated gold can be considered free milling while the remainder is occluded or very finely disseminated within the sulfide matrix.
While the free-milling portion can be recovered by traditional gravity or cyanidation processes discussed above, the sulfide-associated gold can cause issues with these processes. Some sulfide minerals consume large amounts of cyanide or dissolved oxygen (critical to the cyanidation process) and make whole ore leaching impractical or uneconomic. The ultra-fine gold particles associated with sulfide minerals are often too small to recover by gravity and very expensive to liberate by grinding. Typically, sulfide-associated gold is recovered by froth flotation. A typical sulfide-associated gold flowsheet is presented below in Figure 2:
Figure 2: Typical sulfide-associated gold process The crushing, grinding and gravity portion of this process is essentially the same as the free-milling process discussed above. Instead of cyanide leaching of the cyclone overflow, the gold and sulfide minerals are recovered by flotation. The particles in the cyclone overflow are mixed with chemical reagents to render the surfaces of the gold-containing sulfide minerals hydrophobic (metallic gold is naturally hydrophobic). Froth flotation cells then aggressively bubble air through the slurry. The air bubbles attach to the hydrophobic particles in the slurry and float them to the surface creating a mineral froth at the top of the flotation cell. This concentrated mineral froth is then collected from the surface of the flotation cell.
Typically, this concentrate contains a mixture of gold along with other valuable elements found in sulfide minerals such as copper, lead, zinc, etc. The bulk concentrate is most often filtered and sold to a smelter for further refining. In some cases, the flotation concentrates are processed further to produce bullion – this will be discussed in the next section. While gold is naturally hydrophobic and thus amenable to flotation in the particle size range of 75-300 µm, very fine or very coarse gold does not respond well. Along with the benefits of lower CAPEX and reagent consumption mentioned previously, this can make the addition of a gravity circuit even more critical as it will prevent overgrinding of gold and capture any coarse particles before they report to the flotation circuit.
Refractory Gold Any ore that is not readily amenable to recovery by conventional cyanide leaching at a reasonable grind size can be considered refractory. The three primary factors that cause gold ores to be refractory are:
• Physical encapsulation – Extremely fine (<10 µm) particles are locked within an impervious, unreactive mineral.
• Chemical Interference – This occurs when there are minerals in the ore that consume large quantities of cyanide or oxygen.
• Preg-robbing – When the ore contains graphite or other carbonaceous matter; the gold, which often leaches well into solution, is pulled out of the leach solution by the carbonaceous material.
Each of the factors that result in an ore being refractory require a pre-treatment step before the ore can be treated by a conventional cyanidation leach process.
Physical Encapsulation Physical encapsulation can be overcome by ultra-fine grinding; however, this is often not economically viable. If the gold is encapsulated in sulfides, oxidation of the sulfide minerals by roasting, pressure oxidation or bio-oxidation can be employed.
Chemical Interference Various minerals can interfere with the leaching process by consuming cyanide or dissolved oxygen. In the case of pyrrhotite, a notorious oxygen consumer, pre-aeration of the leach slurry before cyanide addition can passivate the sulfide mineral and allow the leach to proceed normally. Both sulfide and oxide copper minerals can be consumers of cyanide. In the case of native copper or oxide copper minerals, sulfuric acid leaching can remove the copper prior to cyanidation.
Sulfide minerals that consume cyanide are typically preconcentrated by flotation before being oxidized using roasting, pressure oxidation or bio-oxidation.
Preg-Robbing Minerals Typically, preg-robbing carbon is managed in one of five ways:
• Carbon in Leach (CIL) – Adding activated carbon (with a much higher adsorptive capacity than natural carbonaceous material) during the leaching process.
• Roasting – Burning off the carbon content eliminates the preg-robbing effects but can be costly to treat the whole ore.
• Blanking – Chemicals such as kerosene or chlorine can deactivate the carbon surfaces and minimize preg-robbing; chlorination is typically more effective but much more expensive than kerosene.
• Pre-flotation – Using froth flotation to float out the naturally hydrophobic carbon ahead of the leaching process.
• Gravity concentration – In recent years gravity concentration has been adapted to deal with carbonaceous ores; organic carbon has a relatively low specific gravity compared to gold or sulfide minerals and can be easily rejected leaving a high-grade, low carbon concentrate for cyanidation.
CONCLUSION When it comes to the gold recovery process, there is no “one size fits all”, but there are plenty of options and solutions. While the correct process depends on the type of gold ore you’re working with and any challenges your project may face – there are many experts who are ready to help you figure those steps out.
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Post by likeike on Aug 11, 2023 21:19:57 GMT
Beginners' Guide to Cut and Fill Mining Method | An Underground Miner by An Underground Miner in Mining / Underground Mining Posted on 03/02/2023 14:14 Determining the best mining method before work begins is critical. Analysis of ore bodies lets miners understand which method will obtain the highest yield and offer the most cost-effective solution. It's also essential for safety. Many methods rely on backfill to create a new working surface - if the fill material isn't up to the task, the mine's structural integrity is at risk. This is true of cut and fill mining (C&F), but some deposits are perfectly suited to this selective mining method. Learn about when this technique should be used, which ore bodies are mined using this method, and how the process works below. ⛏️ How Does Cut and Fill Differ from Other Underground Mining Methods? Cut and Fill mining Method Kelapstick, CC BY 2.0, via Wikimedia Commons This strategy is best suited to steeply dipping metal deposits. It's typically used for high-grade deposits; gold, silver, and copper are all mined using this method. It can be used for deep or shallow bodies but doesn't tend to be used for extremely deep deposits. It uses fill stoping and is favored for areas containing weak or broken rock. While underhand cut-and-fill is sometimes used (where the introduction method progresses from the top down), the most common type is overhand cut-and-fill. In this technique, mining starts at the bottom and progresses generally upward from there. Residual rock is used as fill (combined with composite material varied on the quality of the rock) to form progressive stopes, working from the bottom up. The consolidated fill serves as a new floor and must be sturdy enough to support equipment and staff. As a type of upward mining, this is a very expensive mining method compared to some other techniques. It's a selective method, meaning that low-grade ore and loose fragments are left behind to prioritize thick ore bodies containing high-quality materials. It promises a high yield with when done correctly, which is why it's prioritized for massive deposits of high-grade ore. Smaller and broken ore deposits are left behind or become part of the paste fill. ⛏️ Underground Mining vs. Surface Mining Komatsu bolter at work While this technique is typically used for shallower deposits, it is still a form of underground mining rather than surface mining. The main difference is that in surface mining, extracting ore bodies takes place from an open access point at the mine's surface. In underground mining techniques such as cut-and-fill stoping, the ore body is extracted from beneath and transported back to the surface via a shaft. There are significant expenses associated with any underground method, but techniques like cut-and-fill mining are considered superior for overall ore extraction. The ore makes recovery for the expensive production cycle in this way. To remain economically viable, support pillars must be offset by the size and quality of the ore body. The first support pillar is installed at the top of the mine above the productive area of the cut-and-fill operation. This protects the ventilation area and enables safe worker access. Layers below this are cut in horizontal slices, generally upwards from the bottom of the ore body. ⛏️ How the Cut and Fill Method Works: Step-by-Step horizontal view of cut and fill mining method This method is favored for mining steeply dipping orebodies. Here's how the process works, from exploration to extraction. 1. Determining Ownership The first stage of any mining operation is to determine the project's owner. The owner is responsible for the exploration process and selecting the most suitable method. The mine's depth will be determined and a surface waste storage area scoped out. Local environmental considerations must also be taken into effect. Cut-and-fill mining is often considered a versatile method because it carries less risk of surface collapse than some other underground techniques. 2. Surveying Waste Rock The chemical makeup of waste rock should be assessed. This determines how suitable it will be for use as backfill and what other suitable materials it may be combined with. The dispersal and quality of ore deposits compared to rocky areas needs to be understood to determine where each floor should be. Irregular ore zones containing smaller quantities may be overlooked and used as backfill in favor of thicker, richer deposits. 3. Assessing Backfill Materials Several types of composite backfill may be used in overhand cut-and-fill mining: Hydraulic backfill This is a method that combines waste material with sand fill or other materials to create a suitable floor for the next horizontal slice of the operation. Pneumatic fill This uses pneumatic mining gear to deposit a rock and cement mixture (it may also involve other substances) to create backfill. Loose rock fill This is less commonly used, although it may be used for the upper slice stope as less support is required. Unconsolidated fill is cheaper but less stable. 4. Hydraulic Fill Operations The best backfill method is hydraulic fill, requiring deposition techniques that allow a viscous paste to be transported and deposited in emptied ore spaces. Dilution control is generally easier with this method. This paste-fill method involves creating a dense mixture of materials that will set to form a stable surface. A major advantage of hydraulic sand fill is that it makes moving mining equipment easier, especially heavy drilling gear. This makes it easier to get to where the ore lies and extract it with maximum efficiency. 5. Access Selection Ore passes may be reached via either a shaft or a ramp. Ramps are better for allowing heavy equipment access to lower levels, but shafts may be more cost-effective. Fill stoping access depends on the distribution of the ore pass. Irregular distribution or deeper deposits may make shafts the preferred access method. 6. Choosing Equipment The project's engineering fundamentals may affect which machinery can be used. Layers are typically cut into horizontal blocks which are filled as soon as the area is fully mined. A floor pillar system may be used to stabilize ore overlies while operations are ongoing, but even so, heavy drilling equipment may destabilize especially an especially poor-quality rock overburden. 7. Ensuring Proper Ventilation Raised areas are established at the beginning of the project to allow sufficient ventilation to reach lower levels. The ventilated area is protected by an overhead pillar. 8. Mining Ore In cut-and-fill stoping, high-quality and large deposits are favored to make the operation profitable. It's an excellent technique for reaching irregular deposits, but small or scattered deposits that aren't readily visible or reachable may be overlooked. ⛏️ Cost Considerations for a Cut and Fill Operation Quality of the Ore Body This technique is most commonly used for high-quality deposits. Gold, silver, and copper are some of the most popular materials mined using this technique. They may come in larger, richer deposits that have an irregular structure, making this method more useful than other horizontal methods. Cut-and-fill mining allows for the floor to constantly be replaced using backfill. This means that especially dense deposits can be mined almost completely, regardless of their structure, meaning that the operation is profitable despite the high cost of setting up. Surrounding Rock Quality Another key consideration is the quality of the surrounding rock. Low-quality rock may make other horizontal methods unsustainable or unsafe. While loose or disturbed rock still affects the operation (e.g. it can affect which equipment is considered suitable), this technique is more forgiving of loose rock than methods like room and pillar mining. The amount of backfill required to fill ore void areas depends on the vein's thickness. Ore disassembled ceiling areas are temporarily supported before being filled in with suitable backfill materials. This allows for the productive use of waste rock, which is typically combined with other materials such as sand and slurry. These are generally applied using hydraulic techniques. When weak host rock would make other operations unviable or even unsafe, this technique offers the perfect answer. ⛏️ Frequently Asked Questions What are the 4 surface mining methods? Open-pit mining - this involves a massive pit that gets progressively deeper as more ore is mined. Strip mining - this is most commonly used in coal mining operations. It's similar to open-pit but has a distinct technique for removing the overburden. Highwall mining - this is also used in coal mining. It's a fully mechanized technique for extracting extra ore. Mountaintop removal - this is just what it sounds like! Mountaintops are blasted to extract ore (mostly coal). Dredging is also considered a form of surface mining. It's used to extract ore from submerged areas. What is a cut in mining? The cut is the area that must be excavated to reach an ore deposit. It extends outward from the shaft or ramp. What is Avoca mining method? Like cut-and-fill, the Avoca technique uses loose rock as backfill. However, it's used for slightly different applications and has distinct overcut and undercut layers. What are the 3 techniques used for surface mining? Open-pit Strip Quarrying ⛏️ Summary komatsu driller bolter This technique is used worldwide and is effective for ore bodies that other mining methods would struggle to extract profitably. Despite its complexity, there's a simple elegance to using waste material as a new floor and working upward from the bottom. anundergroundminer.com/blog/beginners-guide-to-cut-and-fill-mining-method
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Post by likeike on Feb 5, 2024 14:47:07 GMT
Drill Result Cheat Sheet by Lobo Tiggre
Wednesday, December 08, 12:00pm, UTC, 2021 When it comes to mineral exploration, almost nothing is more important than drilling. Whether it’s diamond (core), reverse circulation (RC), rotary, percussion, or some other form, only drilling can extract samples from the ground to hopefully define a valuable deposit.
Until a company delivers good, consistent drill results, it has nothing.
No amount of surface sampling, geophysics, “district-scale” land packages, or exciting stories of past production confer any value whatsoever.
A deposit that’s been well drilled and studied, however, can be the basis of a rational valuation of a company. Even banks will lend money on this basis.
That’s why a drill rig is often called a Truth Machine in the business.
So, what are good drill results?
Obviously, there are a lot of variables, from the minerals in question, to the type of deposit, to the stage of exploration.
A proper answer would take a very thick book to do it justice. That’s another item on my long-term to-do list. For now, I hope this cheat sheet will help.
Drill Terminology First off, let’s start with some basic definitions:
Diamond (“core drilling”). This isn’t usually drilling for diamonds (though it can be), but drilling with a diamond-encrusted, tubular drill bit. The diamond bit is attached to tubular drill rods—more and more of them as the drilling penetrates deeper into the earth. This extracts cylindrical samples of stone—“drill core”—in which we can see veins, faults, and other geological information. It also provides material for chemical assay (grade determination). Core drilling provides a greater wealth of information than other types of drilling, but it’s more expensive. Note that there are different sizes of diamond drills: NQ core is 47.6mm, HQ is 63.5mm, and PQ is 85mm. The wider the core, the more data we get, but the slower and more expensive it is. HQ is the most common diameter.
An extra step that’s possible with core drilling is to “orient” the core, so you always know which side is up. This tells us the orientation in the earth of the veins, faults, and other features we find in the drill core. That’s a great help in figuring out Mother Nature’s geological puzzles.
Reverse Circulation (RC). An RC drill is basically a giant vacuum cleaner with a drill bit on the end. This crushes rock into chips and sucks them up to be collected on surface as it goes. Rock chips provide material for the assay labs, but obviously, much detailed information about the features encountered by the drill is lost as the rock is torn up in the process. RC’s great redeeming feature is that it’s usually faster and cheaper than diamond drilling. Because of this, sometimes explorers drill long holes to near target depth with RC, and then finish the hole with diamond drilling to get more information. Shallow. There are various kinds of drill that can’t drill very deep, but they’re relatively cheap and fast. Because of their depth limitations, they can’t define much volume of mineralized rocks, but they can quickly test larger areas for later follow-up with RC or diamond drilling. This disturbs a lot less ground than digging lots of trenches (and in some conditions, like sandy ground, trenching to bedrock can be difficult). I see these as prospecting tools, not resource definition tools. Man-Portable. There’s a type of modular diamond drill, the pieces of which can theoretically be carried by people on foot. This gives access to difficult terrain or environmentally sensitive terrain with minimum disturbance. In practice, the motors are big enough that it would take a team of very burly porters to carry them. The point remains that whether it’s people, donkeys, ATVs, or helicopters, the pieces can be assembled to make powerful diamond drill rigs on steep mountainsides or places with no roads. There are hand augurs and even a “backpack” diamond drill rig, but these are really just shallow sampling tools.
Drilling Purposes With these drill basics in hand, the next thing is to understand what the purpose of the drilling is.
In a first stab at a new target, for instance, any significant hits are a big win. But in upgrading a known deposit to a higher level of confidence category, the results have to be as good as what came before—or better—or they damage the deposit.
One could say that in general, the earlier the stage of exploration, the lower the bar. The more advanced the project, the higher the bar for materially improving a project.
Here are some specific purposes for drilling, and what to look for in the results:
Twinning. This is when a hole (of whatever kind) is drilled right beside and in the same orientation as an existing drill hole. Why duplicate effort? There can be legitimate reasons for this, such as when there’s a database of historic drill results. Successfully twinning a few of these old holes can validate the whole database, saving the new company a lot of time and money. Another valid reason is when some sort of bias or other problem crops up in one form of drilling. RC drilling, for instance, can sometimes “smear” the target mineralization over a wider interval than it really occurs in. Twinning with a diamond hole can tell us if this is happening and help correct for it. The thing to watch out for is when a company twins high-grade holes without any real need, just because they know they’ll likely be able to report another high-grade hit to the market. What’s plain old dishonesty is when they twin a hole and don’t mention that it’s a twin. Almost as bad is when the fact that a hole is a twin is buried in the fine print at the end of a press release. Confirmation. Twinning can be a form of confirmation drilling, but one can confirm known information without twinning an old hole. Just plunk a new one somewhere in the middle of what’s supposed to be a mineralized area and see if the new result matches the old info. Sometimes this is necessary, but too much “confirmation” drilling looks to me like drilling for the market, rather than to define a deposit worth mining. Step-out. A step-out hole is any hole drilled beyond the limits of known mineralization. The idea, of course, is to expand a hopeful deposit. If there’s no known mineralization, drilling can’t be called step-out. Sometimes drilling within the known footprint of a mineralized area but below or above what’s been drilled before is called step-out drilling, but more often it’s called “down-dip” or “up-dip” extensional drilling. Whatever it’s called, if it’s successful it expands the known mineral endowment, and that’s a good thing. If it fails, it doesn’t make what’s there any smaller, but it does limit the potential to expand mineralization in that direction. One thing to watch out for is drilling a long distance off that’s sometimes called step-out drilling. Even if successful, it could be a separate zone if “the dots don’t connect.” For narrow vein-type deposits, holes (dots) more than 25 or even 10 meters away may or may not connect. That makes it a stretch to call a hole 100 or more meters away a step-out hole. For bulk-tonnage targets, it’s a stretch to call holes kilometers away step-outs. Infill. This is drilling within a known mineralized area—but it’s between previous holes (not twinning). This reduces the space between holes (increases “drill density”), providing more detailed information for more accurate modeling of a deposit. Infill drilling doesn’t usually make a deposit any bigger. It increases our confidence that the deposit is actually there and that its continuity, average grade, and mineral composition are well understood. So, positive infill drill results may not make a deposit larger, but they can define it in the first place, then upgrade it from Inferred to Indicated, to Measured, to Proven and Probable mine reserves. That adds value. The thing to watch out for here is results that aren’t as good as previous results. This can lower the grade, reduce the tonnage, or even turn what had seemed like ore into waste. Geotechnical. This isn’t exploration at all, but holes drilled to verify rock characteristics (which impact pit all slopes, tunnel support needs, and more), water flow, and other variables needed for engineering studies. These holes are not necessarily expected to hit good mineralization, so it’s “no harm, no foul” if they have none. But sometimes they surprise us with good results where none were expected—they can even result in new surprise discoveries. Sweet, but don’t ignore the geotechnical results. “Incompetent” rock can lower the angle of pit walls or require more (expensive) rock-bolting and other support in tunnels. These results are highly material to the business of actually making money on a mineral discovery. Condemnation. This is drilling done specifically not to find valuable mineralization. It’s when you already have a deposit and need to figure out where to put the plant, waste dumps, leach pads (if any), and other infrastructure. You don’t want to put any of these things on top of a deposit you haven’t found yet, so you drill holes to “condemn” ground (show that there’s nothing valuable there) before you build. This is a real issue: I’ve been to a mine where they poured concrete foundations for a mill right over a massive sulfide vein that graded over 20 ounces of silver per tonne. There’s no downside here. If condemnation drilling finds nothing, it’s as expected and you know you can put infrastructure there without destroying any value. But if condemnation drilling does make a new discovery, it’s an unexpected plus—usually worth it if you have to move your infrastructure around a bit. Bulk sample. There are different types of bulk samples, taken in different ways. One way is to drill large-diameter holes into known mineralization to extract tonnes of potential ore to process. If metal recoveries conform to model, it’s a success. If not… well, we learned something which may alter or even kill the project. However the bulk sample turns out, the drilling itself into known mineralization matters. As with infill drilling, it can confirm, improve on, or detract from modeled resources in the ground, so watch out for that. Production Drilling. Sometimes a drill hole is a production well. That's not just in the case of oil and gas, but also for in situ (solution mining) production of uranium, copper, and other soluble minerals. Though such wells are drilled for production purposes, they can provide exploration-type results as well, such as flow rates for oil and gas, grades and thicknesses for metals, and a sort for combination for brines like lithium and potassium salts. What we generally want here is a lack of surprises. Better than expected results are fine, but rare; surprises are usually negative. Like infill drilling, production drilling that disappoints reduces the value of a project. Understanding these types of drilling, we have context for evaluating drill results.
Understanding Grade To do that, however, we need one more thing; we need to understand what’s low, average, or high grade?
To do this, the #1 thing to be clear on is that open-pit mining is much cheaper than underground mining. That makes what’s considered high grade for near-surface (open pit) deposits very different from high grade for deposits that would have to be mined underground.
The other thing to keep in mind is that it’s much more expensive to extract metals from some minerals than others. Minerals like enargite are notoriously hard to process. I check with a geochemist when I’m not familiar with the minerals in a deposit I’m looking at.
One major category that’s easy to watch out for is “refractory” ore.
I’ll skip the technical details, but suffice it to say that such ores often require expensive treatment—like roasting in an autoclave—before the metals can be extracted. Refractory ores are common and how to handle them is well understood, so don’t take this as any sort of kiss of death for a project. It just means that the grades need to be higher to pay for the extra processing.
Another major category to watch out for is polymetallic ore.
When ores contain several metals, it can complicate extraction. Miners usually have to pick one metal to concentrate on to maximize the value extracted, at the expense of others that would be more difficult or expensive to recover—if they can be recovered at all.
For example:
Gold and silver often occur together, sometimes in an alloy called electrum. But other times, maximizing gold recoveries means giving up a lot of silver recovery. If there’s copper and gold together, you can run into the problem of the copper using up cyanide before it gets to liberating the gold. If you have a bunch of metals together, like a VMS-type deposit with lead, zinc, copper, gold, and silver, there’s no way you can optimize for all of them. When explorers convert all of these metals to gold (or silver) equivalent, assuming 100% recovery of each, it results in a much higher-grade number than could ever be recovered in practice. This may all sound complicated, and honestly, it is. That’s why I want to see a detailed feasibility study before I back a project developer planning to build a mine.
That said, I have my own rules of thumb for what’s high grade—and what isn’t—that I’m happy to share with you.
Gold Open pit:
0–0.5 g/t gold is low grade. 0.5–1.5 g/t gold is average grade. Over 1.5 g/t gold is high grade. Underground:
0–5.0 g/t gold is low grade. 5.0–8.0 g/t gold is average grade. Over 8.0 g/t gold is high grade. Gold measured in ounces per tonne is “bonanza” grade. Silver Open pit:
0–30 g/t silver is low grade. 30–150 g/t silver is average grade. Over 150 g/t silver is high grade. Underground:
0–150 g/t silver is low grade. 150–350 g/t silver is average grade. Over 350 g/t silver is high grade. Silver measured in kilos per tonne is “bonanza” grade. Copper Open pit:
0–0.5% copper is low grade. 0.5–1.0% copper is average grade. Over 1.0% copper is high grade. Underground:
0–1.0% copper is low grade. 1.0– 3.0% copper is average grade. Over 3.0% copper is high grade. Uranium Athabasca Basin:
0–1% U3O8 is low grade. 1-5% U3O8 is average grade. Over 5% U3O8 is high grade. Rest of the world, in situ (solution mining):
0–100 PPM U3O8 is low grade. 100–300 PPM U3O8 is average grade. Over 400 PPM U3O8 is high grade. Rest of the world, conventional (hard rock mining):
Under 0.1% U3O8 is low grade. 0.2%–1% U3O8 is average grade. Over 1% U3O8 is high grade. I should stress that it’s important to understand that these are not international standards set by some geological authority. These are my numbers, based on what I’ve seen in the field.
Also, as you can see, uranium is an odd duck. In my view, while it might be nice to have something considered “high grade for outside the Athabasca Basin,” it remains a fact that the Athabasca Basin exists. There are several known, large, very high-grade deposits awaiting development in the Athabasca—and more are on the way. I’ve never understood why so many investors apply different standards to non-Athabasca deposits. The object here is to make money, not to give everyone gold stars for making a good effort. I hold deposits everywhere to high economic thresholds. If non-Athabasca deposits can compete (somehow) on margin, that’s fine. If not, why bother?
As for gold, it's worth keeping in mind that oxidized gold mineralization tends to be much cheaper to process than "fresh" sulfide mineralization. Oxide gold that can be mined via open pit and heap leached with little crushing or grinding can be profitable at what I've given as "low grade" above. It can gush cash at what I've given as "average grade." The same dynamic applies to silver, but most silver mines are underground sulfide operations. Just remember not to jump to conclusions when you see "oxide" in press releases. Not all oxide mineralization leaches well. Some require a lot of crushing, agglomeration, and other steps that add costs. A good feasibility study should make clear the value of such mineralization.
Back to the big picture: these rules of thumb for grade are just a starting point:
If the would-be ore is refractory, I want to see higher grades. If it’s polymetallic, I want to see higher grades of the most valuable metal in the mix (by price and quantity). For underground mining of veins and such structures, I want to see high grades over minimum mechanized mining widths. That's at least 1.5 meters, but 2.0 is solid—and the thicker the better. Anything measured in centimeters is suspect. Anything less than half a meter makes it very tough to build enough tonnage to matter—even with bonanza grades. For bulk tonnage open-pit mining, I want to see above-average grades over hundreds of meters. High grades over several tens of meters can work, but there also needs to be high consistency. Narrow low-grade projects need not apply. And so forth… To get more detailed, I have to look at a specific project. For those interested, I do provide such analysis when I evaluate and update companies covered in My Take. That service now covers about 500 resource and mining stocks, and it grows larger every month as readers request coverage of more companies.
But in general, this is how I look at drill results.
I hope you find it useful.
P.S. To be kept abreast of more opportunities, dangers, and issues affecting investors, please sign up for our free, no-spam, weekly Speculator’s Digest.
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Post by likeike on Mar 25, 2024 21:05:20 GMT
by @teevee on 25 Mar 2024, 12:21 How I Pick Junior Resource Companies Public junior resource companies are perhaps the riskiest sector of markets, but can also provide the largest capital gains. To reduce risk, I focus on a number of criteria, and will use $OPHR and $PMET to illustrate my process:
1. There are two primary categories, namely pre discovery and post discovery of significant drill results that suggest good potential for a tier 1 deposit. A post discovery company is usually immediately rewarded with a significant increase in share price, often 2x to 5x, making it more expensive to build a share position, but with reduced risk. $PMET is a good example of a company that rose 2x to 3x on discovery and is where I started building a large share position. The share price of pre discovery companies are usually reflected by low share prices, facilitating the opportunity to build large share positions at a relatively low cost. $OPHR is a good example of a pre discovery junior resource company where I have built a substantial position.
2. Geology is a critical aspect in selecting a junior explorer in which to put money in harms way. OPHR's Radis and Pelipas projects both exhibit very prospective geology to host large spodumene pegmatite deposits. There are initial spodumene discoveries at Radis with about 80% of the project area yet to be prospected within the Yashinski Greenstone Belt. The Pelipas project is located in what appears to be the nexus for pegmatites in this section of the Eastmain Greenstone Belt and exhibits the correct K/Rb ratios, LCT pathfinders and structural setting to host very large spodumene pegmatites. At both Radis and Pelipas, satellite imagery suggests there are numerous large pegmatites awaiting a "boots and hammers" first pass with drilling to follow later in 2024. PMET's geology has been proven to host at least one tier 1 deposit and a handful of satellite deposits, any one of which may eventually prove to rival CV-5.
3. Management is also important. I have to see they have a track record of being able to raise equity capital on an ongoing basis, with as little dilution as possible. PMET has demonstrated this on all financings to date, as has OPHR's management. Prudent management of equity capital is also very important, with the bulk of expenditures directed towards exploration and drilling.
4. Participation in financings are a good way to build positions at a fixed price. I did not have the opportunity to participate in early PMET financings, but added to my position in the market near financing prices. I have participated in OPHR financings and used them to build my share position in addition to market share purchases.
5. Buy and hold or trade? This is dependant upon ongoing drill results and position sizing. Trading positions are generally smaller and sized to average trading volumes to maximize liquidity. I take large positions that are difficult or impossible to trade, and add to my positions on positive ongoing drill results. I continue to buy PMET on dips and have recently added to OPHR. In the past, I had great success with a buy and hold strategy with DFR (Diamond Fields and their Voisey's Bay discovery), DMM (Diamet Ekati discovery), Delaware Resources (SNIP gold mine) being a few examples. The downside of a buy and hold strategy is that losses are larger when exploration results disappoint, however, the phenomenal gains from buying and holding and continuing to add to winners far exceeds losses from the losers.
In summary, OPHR is an attractively priced pre discovery junior explorer with a good management team , projects that exhibit favourable geology, and ability to raise capital on an ongoing basis, making it an attractive speculation , and PMET continues to offer good upside for an advanced and under priced tier 1 discovery.
Disclosure: As indicated above I have long positions in OPHR and PMET and have no affiliation with either company.
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