Mining glossary

A mine where work has stopped and no one is maintaining the site.^1,2

Abandoned mines can have open shafts and hazardous water.

See also: rehabilitation

Acidic water that forms when sulphide minerals in exposed rock react with air and water, and can carry dissolved metals into streams.³

Pyrite-rich waste rock can cause acid drainage for decades.

See also: waste rock, mine drainage

A royalty calculated as a percentage of the value of the mineral sold.⁴

A state may charge a set percentage of the value of iron ore sold.

See also: royalty

A horizontal or near-horizontal tunnel driven from a hillside into a mine, used for access, drainage or hauling ore.^1,5

Cornish adits drained water from deep workings by gravity.

See also: shaft, winze

A survey flown from an aircraft that records small variations in the Earth's magnetic field to map rock types and structures.⁶

A magnetic map shows a buried intrusion.

See also: geophysics

A measure of what it costs a gold miner to produce an ounce, including mining, processing, administration, sustaining capital and some other costs.⁷

Companies report AISC per ounce each quarter.

See also: cash cost

A deposit of sand, gravel and heavy minerals laid down by running water, often worked for gold, tin or diamonds.^5,8

Alluvial gold sparked the Australian gold rushes of the 1850s.

See also: placer, panning

Change in a rock's minerals caused by hot fluids, which can form haloes around ore deposits.⁹

Potassic and phyllic alteration surround porphyry deposits.

See also: porphyry copper deposit

Aluminium oxide, made from bauxite in a refinery and then smelted to make aluminium metal.⁷

Western Australia has large alumina refineries.

See also: bauxite, Bayer process

A measured value, such as high copper in soil or a magnetic high, that stands out from the background and may point to mineralisation.⁹

A geophysical anomaly is drilled to test for sulphides.

See also: geochemistry, geophysics

A laboratory measurement of how much of a metal or mineral a sample contains.⁶

A fire assay measures gold in a rock sample.

See also: fire assay

The mine laboratory where samples were tested for mineral content.⁵

Count houses and assay houses stood near big Cornish mines.

See also: assayer

A person who tests ores and metals to measure their metal content, historically in an assay house at a mine or mint.⁵

The assayer weighed the gold button and gave the result.

See also: assay, assay house

Work required each year on a US mining claim to keep it valid, now replaced for most claims by an annual fee.¹⁰

Claimants once did assessment work, now pay a maintenance fee.

See also: claim

A shallow method using a screw-shaped rod to bring up soil or soft rock samples.⁶

Auger holes are used to sample soils for geochemistry.

A fan, often with ducting, that sends air to a working place off the main air stream.¹

Auxiliary fans clear blast fumes from a dead-end drive.

See also: ventilation

The compass direction in which a drill hole is pointed, measured in degrees from north.⁶

A hole drilled at azimuth 090 heads east.

See also: dip, collar

Waste rock, tailings or paste placed back into mined-out stopes to support the ground and reduce waste at the surface.¹¹

Cemented paste backfill lets miners remove adjacent pillars.

See also: stope, paste tailings

A woman or girl employed at the surface of a Cornish mine, usually dressing ore.⁵

Bal maidens broke ore with hammers.

See also: bucking

A rotating drum filled with steel balls that grinds ore to fine powder.¹²

A ball mill often follows a SAG mill.

See also: SAG mill, grinding

A barrier that blocks people, vehicles or flying material from entering an unsafe area.¹

A barricade closes a blast area.

See also: blasting

A rock rich in aluminium hydroxide minerals formed by tropical weathering, the main ore of aluminium.⁷

Bauxite is refined to alumina and then smelted to aluminium.

See also: alumina

The chemical method that dissolves aluminium from bauxite in hot caustic soda to make alumina.⁷

Bayer refineries leave red mud as waste.

See also: bauxite, alumina

A type of steam engine with a large rocking beam, used in Cornish mines for pumping and winding.⁵

Beam engines drained deep Cornish mines.

See also: engine house

Any step that upgrades ore before smelting or sale, such as crushing, washing and concentrating. Governments also use it to mean local value-adding.³

Beneficiation plants raise iron ore grade.

See also: concentrate

A mound of material along the edge of a haul road that limits a vehicle's progress towards a drop.¹

Berms are required on elevated roads.

A barren sample inserted among real samples to check for contamination in preparation or analysis.⁶

A blank that returns a high value suggests contamination.

See also: quality control, standard (assay)

A hole drilled in rock to hold explosives for blasting.¹

Blast holes are drilled in a grid across a bench.

See also: blasting

Breaking rock with explosives loaded into drilled holes.^1,13

Blasting at a pit follows a set pattern and timing.

See also: blast hole, misfire

A low-cost underground method in which a large block of ore is undercut so that it breaks and falls under its own weight to be drawn off below.⁹

Block caving is used on large, steep porphyry copper bodies.

See also: underground mining

A three-dimensional grid of cells, each given an estimated grade and rock type, used to estimate resources and plan a mine.⁶

A model with 10 m blocks is used to design an open pit.

See also: resource model, kriging

An early small tin smelting furnace using charcoal as fuel.⁵

Blowing houses stood by streams that powered bellows.

See also: smelting

Rock made of broken, angular fragments cemented together, often formed by explosive fluid release in ore systems.¹⁴

Breccia pipes can carry copper, gold and uranium.

See also: epithermal deposit

Salty groundwater, which in dry basins can hold lithium, potash or boron and is pumped to ponds for evaporation.⁷

Lithium is pumped as brine from salars in the Andes.

See also: salar, evaporation pond

Exploration or development near an existing mine or infrastructure.¹⁴

A brownfield expansion uses the existing plant.

See also: greenfield

Breaking copper ore on an anvil to small pieces with hammers, a task of bal maidens.⁵

Bucking followed cobbing.

See also: bal maiden, cobbing

A shallow device in which fine crushed tin ore was separated by gravity as water flowed over it.⁵

Tin from the stamps was graded in a buddle.

See also: stamp mill

A metal or mineral recovered as a secondary output of mining another commodity, such as cobalt from copper or silver from lead and zinc.⁷

Gallium, germanium and indium are mostly by-products.

See also: co-product

The solid product of roasting or calcining, such as zinc oxide from roasted zinc concentrate, or lime from limestone.^5,7

Zinc calcine is leached in an electrolytic zinc plant.

See also: roasting

A furnace in which ores were roasted to drive off sulphur and arsenic.⁵

Cornish tin ore was calcined before smelting.

See also: roasting

Money spent to build, expand or sustain a mine, such as equipment, plants and shafts.⁶

A new mill is capital expenditure.

See also: operating cost

A variant of carbon-in-pulp in which carbon is in the leach tanks, so gold is picked up while leaching.¹⁵

CIL helps if the ore robs dissolved gold.

See also: carbon-in-pulp

A process in which gold dissolved in cyanide slurry is adsorbed onto activated carbon grains, then stripped off for recovery.¹⁵

CIP and CIL circuits are widely used for gold.

See also: cyanidation

An unusual igneous rock made mostly of carbonate minerals, which can host rare earths and niobium.¹⁶

Carbonatites host rare earth mines in Australia and China.

See also: rare earth element

A status in which a mine is stopped but kept safe and ready to restart, with minimal staff.⁴

Several WA nickel and lithium operations went on care and maintenance in 2024-25.

See also: mine closure

The direct cost of producing a unit of metal, not including most capital spending, depreciation or financing.⁷

A copper mine reports cash cost per pound after by-product credits.

See also: all-in sustaining cost

Tin oxide, the main ore mineral of tin, found in veins and in alluvial gravels.¹⁷

Cornish streamers worked cassiterite from river gravels.

See also: tin streaming

The refined metal sheet plated onto an electrode in electrowinning or electrorefining, such as grade A copper cathode.⁷

Copper cathode is traded on exchanges.

See also: electrowinning

Wording that warns readers when a production target or forecast rests partly on Inferred resources or on early-stage studies.⁶

A scoping study release notes that Inferred resources make up part of the mine plan.

See also: scoping study, Inferred Resource

The most common copper ore mineral, a copper iron sulphide.⁹

Chalcopyrite is the main copper mineral in porphyry deposits.

See also: sulphide

The Canadian Institute of Mining, Metallurgy and Petroleum standards that define resource and reserve categories for use in NI 43-101.¹⁸

NI 43-101 points to the CIM definitions for Inferred, Indicated and Measured resources.

See also: NI 43-101, Mineral Resource

A defined piece of ground in which a miner has the legal right to search for and mine minerals.¹⁰

A US lode claim gives rights over the vein.

See also: lode, placer

A second output of a mine that is important enough to share the cost and revenue with the main product.⁹

Gold may be a co-product of a copper mine.

See also: by-product

Breaking waste off ore fragments with long-headed hammers, as part of ore dressing.⁵

Cobbing was done before bucking.

See also: bucking

The point at the surface where a drill hole starts, given by its coordinates and elevation.⁶

A collar table lists each hole's easting, northing, elevation, dip and azimuth.

See also: azimuth, dip, drill hole

The general term for reducing rock size by crushing and grinding, which uses much of a mine's energy.¹⁹

Comminution is among the largest users of electricity at a concentrator.

See also: crushing, grinding

Under JORC, a member of a recognised professional body with enough relevant experience who takes responsibility for the reported results, resources or reserves.⁶

The last paragraph of an ASX release names the Competent Person and confirms consent.

See also: JORC Code, Qualified Person

In mine safety rules, a person with the ability and experience to carry out an assigned duty. It is different from the reporting-code term.^1,20

MSHA training rules use the term.

See also: Competent Person

An independent report on a company's mineral assets prepared by a Competent Person, often required in a listing document.⁶

An AIM float includes a Competent Person's Report on the mine.

See also: Competent Person, JORC Code

The product of a concentrator, with much more metal per tonne than the ore, sold to smelters or refineries.²¹

A copper concentrate carries far more copper per tonne than the ore it came from.

See also: flotation, smelter

A plant that crushes, grinds and separates ore to make a concentrate.²²

The concentrator treats 40,000 tonnes of ore a day.

See also: concentrate, flotation

The amount of metal in a resource or reserve before mining and processing losses, found by multiplying tonnes by grade.⁶

200 Mt at 0.45 per cent copper contains 900,000 tonnes of copper.

See also: grade, recovery

A store kept by a geological survey or company where drill core can be inspected.^2,6

Researchers visit a state core library to re-examine old core.

See also: drill core

A tray, often wooden or plastic, in which drill core is laid in order of depth for logging and storage.⁶

Trays are photographed wet and dry before sampling.

See also: drill core, core library

The mine office, where wages, accounts and ore sales were handled.⁵

The count house was the mine's office.

See also: assay house

A rocking wooden box used to wash alluvial gold, faster than a pan.⁸

Diggers worked alluvial gold with a pan or a cradle.

See also: panning, sluice

An ancient, stable block of continental crust, such as the Yilgarn in Western Australia or the Kaapvaal in southern Africa.¹⁵

Most of the world's gold and diamonds sit on or near cratons.

See also: greenstone belt

The edge of an ancient craton, where deep faults can carry diamond-bearing magma or other fluids to the surface.¹⁵

Diamond provinces often sit on craton margins.

See also: craton, kimberlite

The Committee for Mineral Reserves International Reporting Standards, which sets a template that national reporting codes follow so that resource categories match across countries.^6,23

JORC, NI 43-101, SAMREC and S-K 1300 all follow the CRIRSCO template.

See also: JORC Code, NI 43-101, SAMREC

A mineral that a government sees as essential to its economy or security and at risk of supply disruption. Lists differ by country.⁷

The United States and Canada each publish their own critical minerals list.

See also: rare earth element

A tunnel driven across the trend of a vein or ore body, often to reach it from a shaft.¹⁴

A crosscut connects the shaft to the lode.

See also: drive, level

Breaking mined rock into smaller pieces, the first stage of processing.^5,7

A primary crusher takes run-of-mine rock.

See also: grinding, comminution

The lowest grade at which material is treated as worth mining or reporting. A lower cut-off adds tonnes and lowers average grade.^6,23

Moving the cut-off from 0.5 to 0.3 g/t gold raises tonnes but lowers the average.

See also: grade, strip ratio, Mineral Resource

Dissolving gold and silver from ore with a dilute cyanide solution, then recovering them from the solution.⁷

Most of the world's gold is recovered by cyanidation.

See also: carbon-in-pulp, heap leach

A sloping tunnel, usually driven in a spiral or zigzag, that lets vehicles drive from the surface to underground workings.¹

Trucks use a decline to carry ore from a deep gold mine.

See also: shaft, underground mining

A gravity method in which crushed rock is put in a liquid of controlled density so that heavy minerals sink and light waste floats.⁷

DMS is used for diamonds, coal and some lithium ores.

See also: gravity separation

A device containing a small explosive charge used to set off a larger explosive.¹

Electric and non-electric detonators fire blast holes.

See also: blasting

Removing water from a slurry or concentrate, using thickeners and filters.²⁴

Concentrate is filtered before shipping.

See also: thickener

Drilling with a hollow bit set with industrial diamonds that cuts a solid core of rock, which is brought up for logging and assay.⁶

Diamond core is used to confirm geology and take metallurgical samples.

See also: reverse circulation drilling, drill core

Waste or low-grade rock mixed with ore during mining, which lowers the delivered grade.^6,23

A 10 per cent dilution lowers the head grade.

See also: ore loss, modifying factors

The angle at which a drill hole, vein or rock layer slopes downward from horizontal.⁶

A hole with a dip of minus 60 degrees heads down at 60 degrees.

See also: azimuth, strike

Ore shipped with little more than crushing and screening, not needing a concentrator.²⁵

High-grade hematite is direct shipping ore.

See also: hematite, beneficiation

The rate used to convert future cash flows into present value.²³

An 8 per cent discount rate is a common assumption in studies.

See also: net present value

Under US mining law, finding a valuable mineral deposit, which is needed before a claim is valid.¹⁰

A claimant must show discovery of a valuable mineral deposit.

See also: claim

Ore minerals spread through the rock as small grains rather than concentrated in veins.⁹

Porphyry copper is disseminated and mined in bulk.

See also: vein

The length of an intercept measured along the drill hole, which may be longer than the real thickness of the zone.⁶

A hole drilled along a thin vein can show a long downhole width.

See also: true width, intercept

A floating machine that digs gravel from a river or pond bed and processes it to recover gold, tin or other heavy minerals.^3,11

Dredges worked rivers in the Klondike and New Zealand.

See also: placer, alluvial deposit

The area at the surface of a mine where ore was crushed and concentrated.⁵

Dressing floors were noisy with stamps and running water.

See also: stamp mill

The solid cylinder of rock produced by diamond drilling, which geologists log and cut in half for assay.⁶

Half of the core goes to the laboratory and half stays in the tray.

See also: diamond drilling, core tray

A hole bored into the ground to sample rock or to test for mineralisation, identified by a hole number such as PTD-014.⁶

A company may drill 40 holes in a campaign.

See also: collar, intercept

A horizontal tunnel driven along a vein or ore body underground.⁵

A drive follows the lode for 300 m.

See also: level, crosscut

A second sample split from the same material to test sampling precision.⁶

Field duplicates test how repeatable sampling is.

See also: quality control

Recovering metal from a leach solution by passing an electric current through it so the metal plates onto a cathode.²⁶

Electrowinning produces cathode copper from solution.

See also: SX-EW

A building that held the steam engine used for pumping, winding or crushing at a mine. Many survive in Cornwall.⁵

Ruined engine houses mark the Cornish landscape.

See also: beam engine

A gold-silver deposit formed from hot water near the surface, within a few kilometres of the surface, often in volcanic areas.¹⁴

Epithermal veins are mined in Mexico, Nevada and the Andes.

See also: vein, porphyry copper deposit

A passage by which people can leave a mine in an emergency.¹

Underground mines must keep an escapeway clear.

A shallow pond where brine is left to evaporate in the sun to concentrate salts such as lithium.⁷

Brine moves through a series of ponds over many months.

See also: brine, salar

The search for mineral deposits and the work to define them, from mapping and sampling to drilling.⁶

A junior spends a year on exploration before reporting a resource.

See also: prospecting, drill hole

A permit that lets a holder explore an area for minerals but not mine commercially.²

An exploration licence is held for a set period and renewed on conditions.

See also: tenement, mining lease

Data and information from exploration, such as drill intercepts, geochemistry and geophysics, that has not yet been turned into a resource estimate.^6,23

A news release listing 12 m at 2.4 g/t gold in a drill hole is an Exploration Result.

See also: Exploration Target, intercept, drill hole

A JORC term for a conceptual range of tonnes and grade in an area where drilling is too sparse to report a resource. It must be stated as ranges and as not yet a resource.⁶

A company may say 80 to 120 Mt at 0.8 to 1.2 g/t gold is a target, with a statement that it is conceptual.

See also: Exploration Results, Mineral Resource, JORC Code

A fall of rock from the roof or walls of an underground opening, one of the main causes of mining deaths.¹

Ground support reduces falls of ground.

See also: ground control

A detailed technical and economic study of the chosen development option, with full assessment of modifying factors and financial analysis. Lenders usually rely on it before construction.^6,23

A definitive feasibility study (DFS) sets the capital cost used in a financing.

See also: pre-feasibility study, modifying factors

A laboratory method for gold, silver and platinum group metals in which a sample is fused with fluxes, the metal collected in lead, then weighed.⁶

Gold in drill samples is usually measured by fire assay.

See also: assay, ICP

A gas that will burn in the normal concentration of oxygen in air.¹

Methane is a flammable gas.

See also: methane

A method that separates valuable minerals from waste by making the wanted minerals cling to air bubbles in a water slurry and float to the surface as froth.^3,21

Copper sulphide ore is concentrated by flotation.

See also: concentrate

The loss of a mining claim, for example when fees or filings are not made on time.¹⁰

A claim not maintained can be forfeited.

See also: claim

Another name for flotation: bubbles carry chemically treated mineral particles to the surface where they are skimmed off.^3,21

Froth flotation turns finely ground copper ore into a concentrate.

See also: flotation

Grams per tonne, the usual unit for gold, silver and platinum group metal grade. One gram per tonne equals one part per million.¹⁴

2.4 g/t gold means 2.4 grams of gold in each tonne of rock.

See also: grade, ppm, troy ounce

Lead sulphide, the main ore mineral of lead, often carrying silver.²⁷

Galena is mined with sphalerite in many zinc-lead deposits.

See also: sphalerite

The worthless minerals mixed with ore minerals, such as quartz in a gold vein, which are removed during processing.²⁸

Quartz and carbonate are common gangue in gold ore.

See also: ore, waste rock

The US law that lets citizens locate mining claims for hard-rock minerals on federal land.¹⁰

The 1872 law is still the main law for hard-rock claims on federal land.

See also: claim, lode claim

The study of the chemistry of rocks, soils and waters to find anomalies that point to mineral deposits.⁶

A soil survey shows a copper anomaly 800 m long.

See also: soil sampling, anomaly

A government body that maps geology, holds data and publishes information on mineral resources.²

The Geological Survey of Western Australia publishes maps and data.

See also: open file report

The use of physical measurements, such as magnetic, gravity, electrical and seismic surveys, to infer what lies below the surface.⁶

A magnetic survey outlines an iron-rich body under cover.

See also: anomaly, induced polarisation

A shallow dish in which a prospector swirls gravel and water to wash away light material and leave heavy gold.⁸

Panning was the main method early in the Australian rushes.

See also: panning, cradle

An iron-stained cap of weathered rock over a sulphide deposit, a clue prospectors have used for centuries.¹⁹

A rusty gossan led explorers to a buried copper-zinc body.

See also: prospecting

The concentration of a valuable metal or mineral in rock, given as grams per tonne, per cent by weight or parts per million.^6,7

A copper deposit may grade 0.45 per cent copper.

See also: g/t, ppm, cut-off grade

Close-spaced drilling and sampling in an active mine to decide which blocks are ore and which are waste.⁶

Blast-hole sampling guides grade control in a pit.

See also: reconciliation

Separating minerals by differences in density, for example with jigs, spirals, tables or heavy media.³

Gravity circuits recover coarse gold and tin.

See also: jig, dense media separation

Exploration or development in a new area with no existing mine or infrastructure.⁶

Greenfield exploration is high risk.

See also: brownfield

An ancient belt of volcanic and sedimentary rocks, often metamorphosed, that hosts gold and nickel in places such as Western Australia and Canada.¹⁵

The Yilgarn craton has many greenstone belts.

See also: orogenic gold deposit

Reducing crushed ore to a fine powder in mills so valuable minerals are freed from waste.⁷

Ball mills grind ore in rotating drums.

See also: crushing, SAG mill

The set of methods used to keep the rock around mine openings stable, including support, bolting and scaling.¹

Ground control plans are required in underground mines.

See also: rock fixture, scaling

The average grade of the ore as it enters the processing plant.⁶

A mill feeding 1.2 g/t ore has a head grade of 1.2 g/t.

See also: tail grade, recovery

A process in which crushed ore is piled on a lined pad and sprayed with a leaching solution that trickles through and carries metal out for recovery.^14,21

Gold and copper oxide ores are often heap leached.

See also: leaching, SX-EW

Beach or dune sands rich in dense minerals such as ilmenite, rutile, zircon and monazite.²⁹

Mineral sands are mined along the coasts of Australia, South Africa and Mozambique.

See also: placer

An iron oxide mineral that is the main ore of iron in direct-shipping ore.⁷

Hematite ore from the Pilbara is shipped with little processing.

See also: iron formation

The steep wall of an open pit or quarry left above the working floor, or the unmined face that remains after a cut.^1,13

Loose rock on the highwall is scaled to make it safe.

See also: scaling

A machine with a drum or wheel that raises and lowers people, ore and materials in a shaft.¹

Hoist ropes are inspected for wear.

See also: shaft

The rock that surrounds or contains an ore deposit.⁹

The host rock to the gold veins is basalt.

See also: ore, orebody

Using high-pressure jets of water to wash away hillsides of gravel for gold recovery.³

Hydraulic mining moved vast quantities of gravel.

See also: placer

Extracting metal using liquids, as in leaching, solvent extraction and electrowinning.⁷

Heap leach and SX-EW is a hydrometallurgical route.

See also: pyrometallurgy

Involving hot water solutions that carry dissolved metals and deposit them in cracks and pores.¹⁴

Most vein gold is hydrothermal.

See also: vein, epithermal deposit

Inductively coupled plasma, an instrument technique used by laboratories to measure many elements in a dissolved sample at once.⁹

Lithium and base metal assays often use an acid digest with ICP finish.

See also: assay, fire assay

Leaching metal from the ore body underground by pumping solution through wells, and bringing the solution to the surface. It is used for uranium and some copper.³

ISR avoids digging ore out of the ground.

See also: roll-front uranium

A resource category where drilling and sampling are close enough to assume geological and grade continuity with reasonable confidence. It can support a Probable Reserve once modifying factors are applied.^6,23

Holes on a 50 m by 50 m grid might support Indicated status for a gold lode.

See also: Inferred Resource, Measured Resource, Probable Reserve

An electrical survey method that detects disseminated sulphide minerals by how the ground holds a charge.⁹

IP surveys are widely used to target porphyry copper systems.

See also: geophysics

The least certain resource category. Geological evidence suggests continuity, but it is not verified, and the estimate rests on limited sampling. It cannot be converted directly to a reserve.^6,23

A company with only wide-spaced drilling may report most of its tonnes as Inferred.

See also: Indicated Resource, Measured Resource, Mineral Resource

The length of a drill hole that passes through mineralisation at or above a stated grade, quoted with its starting depth.⁶

12 m at 2.4 g/t gold from 85 m is an intercept.

See also: true width, downhole width, collar

A body of molten rock that pushed into other rock and cooled, often the heat and fluid source for ore deposits.⁹

The intrusion drives a hydrothermal system.

See also: porphyry copper deposit

Rare earths adsorbed on clay minerals in deeply weathered granite, mined in southern China and being explored elsewhere.⁷

Ion-adsorption clays are rich in heavy rare earths.

See also: rare earth element

Banded sedimentary rock rich in iron oxide and silica, the main source of iron ore.²⁵

Banded iron formations underlie the Pilbara and the Hamersley Range.

Also IOCG, a large deposit of copper and gold with abundant iron oxide, such as Olympic Dam in South Australia.³⁰

IOCG systems can also hold uranium and rare earths.

See also: porphyry copper deposit

A device that separates heavy from light particles by pulsing water through a bed of material.⁵

Jigs were used to concentrate tin and lead ores.

See also: gravity separation

An arrangement in which two or more companies share ownership and costs of a project.⁷

Owners of a mine are often joint venture partners.

See also: operator

The Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves. Companies listed on the ASX and NZX must follow it. The current edition is 2012.⁶

An ASX release on drill results includes a JORC Table 1.

See also: Competent Person, JORC Table 1, CRIRSCO

The checklist attached to JORC reports that explains sampling, drilling, assaying, geology and estimation methods criterion by criterion, on an if-not-why-not basis.⁶

Table 1 shows whether holes were reverse circulation or diamond and how samples were split.

See also: JORC Code, Competent Person

A volcanic rock that brings diamonds from the mantle to the surface in carrot-shaped pipes.^9,31

The Big Hole at Kimberley follows a kimberlite pipe.

An ancient, very hot, magnesium-rich lava that hosts nickel sulphide deposits in places such as Kambalda in Western Australia.³²

Kambalda nickel comes from komatiite flows.

See also: ultramafic, magmatic sulphide deposit

A geostatistical method that estimates grade at unsampled points by weighting nearby samples according to how grade varies with distance.³⁰

Ordinary kriging is a common way to fill a block model.

See also: block model

A nickel-cobalt deposit formed by deep tropical weathering of ultramafic rock, found in places such as New Caledonia, Indonesia and the Philippines.³³

Laterite ore is mined from shallow pits and processed by leaching or smelting.

See also: saprolite, limonite

A pegmatite enriched in lithium, caesium and tantalum.¹⁷

Greenbushes in Western Australia is a famous LCT pegmatite.

See also: pegmatite, spodumene

Dissolving a wanted metal from ore or concentrate with a chemical solution.^3,21

Gold is leached with cyanide, copper with acid.

See also: heap leach, cyanidation

A horizontal tunnel at a given depth in an underground mine, from which ore is mined.⁵

The 600 m level is the main haulage level.

See also: drive, crosscut

The degree to which valuable mineral grains are freed from waste rock by grinding so they can be separated.²⁷

Fine-grained ore needs finer grinding for liberation.

See also: grinding

The planned number of years a mine can operate based on its reserves and plan.^6,23

A life of mine of 12 years means 12 years of reserves at planned rates.

See also: Ore Reserve

An iron-rich, yellow-brown weathering product of rock, forming the upper layer of laterite nickel profiles.³³

Limonite ore is lower in nickel but higher in cobalt.

See also: saprolite, laterite nickel deposit

LCE, a way to compare lithium products by converting them to the amount of lithium carbonate they would make.⁷

A spodumene concentrate is quoted by LCE content.

See also: spodumene, lithium hydroxide

A lithium chemical used in many battery cathodes, made from spodumene or from brine-derived lithium carbonate.⁷

Hydroxide plants convert spodumene concentrate.

See also: lithium carbonate equivalent

A vein or zone of mineralised rock in place in the host rock, as opposed to loose deposits in gravel.¹⁰

A gold lode runs for 3 km along a shear zone.

See also: vein, placer

A US mining claim on a vein or lode of hard-rock minerals.¹⁰

A lode claim is staked on a vein.

See also: placer claim

A coal-mining method in which a shearer moves back and forth along a long face while roof supports advance behind it.²⁸

Longwall is used in large underground coal mines.

See also: room and pillar mining

A secure facility for storing explosives, blasting agents or detonators.¹

Detonators are stored apart from explosives.

See also: blasting

A nickel-copper deposit, often with platinum group metals, formed when sulphide melt separated from magma and sank.³²

Magmatic sulphides are mined at Sudbury and Norilsk.

See also: laterite nickel deposit

Using magnets to pull magnetic minerals such as magnetite away from non-magnetic waste.^3,25

Magnetic separation upgrades magnetite ore.

See also: magnetite

A magnetic iron oxide mineral, an important iron ore and a mineral that makes magnetic surveys useful.⁷

Magnetite is concentrated by magnetic separation.

See also: iron formation, magnetic separation

A fan that controls the airflow of an entire mine or a major air circuit.¹

The main fan sits at the top of the return airway.

See also: ventilation

An annual fee paid to the BLM to hold an unpatented mining claim or site.¹⁰

The fee replaces yearly assessment work.

See also: assessment work

A vehicle or train that carries people to and from underground workings.¹

Miners ride the mantrip to the face.

See also: decline

A rock made mostly of sulphide minerals such as pyrite, chalcopyrite and sphalerite.¹⁹

Massive sulphide may be 60 per cent or more sulphide.

See also: volcanogenic massive sulphide deposit

A molten mix of metal sulphides produced in smelting, that is further converted to metal, as in copper matte or nickel matte.³⁴

Nickel matte is refined to nickel metal.

See also: smelting, slag

The most certain resource category, backed by close-spaced data so that geology and grade continuity are confirmed. It can support a Proved Reserve.^6,23

Grade-control drilling inside an operating pit often defines Measured material.

See also: Indicated Resource, Proved Reserve, Mineral Resource

A single figure that expresses several metals as one, such as gold equivalent, using assumed prices and recoveries that must be disclosed.⁶

An AuEq figure combines gold and silver.

See also: g/t, cut-off grade

Laboratory and pilot tests on ore samples to find out what recovery and product quality a process can reach.⁶

Test work tells a study what recovery to assume.

See also: recovery, feasibility study

A flammable gas released from coal and some other rocks, which can explode when mixed with air.¹

Coal mines monitor methane.

See also: outburst

The planned end of mining, including removing structures, making the site safe and restoring land.¹¹

Closure plans are required before approval of many mines.

See also: rehabilitation

Water that drains or is pumped from a mine, which may need treatment before release.³

Mine drainage limits are set for iron and suspended solids.

See also: acid mine drainage

Instruction in hazards, procedures and emergency response required before people work at a mine. In the US it is set by MSHA rules.²⁰

New miners get training before they start.

See also: competent person (safety)

A US document that conveys title to federal land and minerals to a claimant.¹⁰

A patent turns a claim into private land.

See also: claim

The value of what a mine produces after subtracting its costs of extraction and a normal return to the producer. The World Bank reports it as a share of GDP.⁷

Mineral rents measure resource wealth to a country.

See also: royalty

The term used in NI 43-101 and S-K 1300 for the economically mineable part of a Measured or Indicated Mineral Resource. It is the same idea as a JORC Ore Reserve.^18,23

A US-listed miner under S-K 1300 reports proven and probable mineral reserves in its annual report.

See also: Ore Reserve, NI 43-101, S-K 1300

A concentration of material in or on the Earth's crust that has reasonable prospects for eventual economic extraction, with a stated quantity, grade and level of geological confidence. It is split into Inferred, Indicated and Measured categories.^6,23

A release might state 40 Mt at 1.1 g/t gold Indicated and 12 Mt at 0.9 g/t gold Inferred at a 0.5 g/t cut-off.

See also: Ore Reserve, Inferred Resource, Indicated Resource, Measured Resource, cut-off grade

The presence of valuable minerals in rock at higher than normal concentration, whether or not it is economic.⁶

Drill hole shows 40 m of copper mineralisation.

See also: ore, grade

A granted right to mine a defined area, under the mining law of the country or state.^2,10

A project cannot start mining until the lease is granted.

See also: tenement, royalty

The complete or partial failure of a blasting charge to explode as planned.¹

Miners must treat a misfire as live explosive until cleared.

See also: blasting

The practical considerations applied to a resource to decide whether it can become a reserve: mining, processing, metallurgy, infrastructure, costs, markets, legal, environmental, social and government factors.^6,23

Poor metallurgical recovery can stop an Indicated resource from becoming a reserve.

See also: Ore Reserve, pre-feasibility study, feasibility study

A phosphate mineral that contains rare earths and sometimes thorium, found in mineral sands and carbonatites.²⁹

Monazite is a source of light rare earths.

See also: rare earth element

The Mine Safety and Health Administration, the US federal agency that enforces mine safety and health laws.²⁰

MSHA inspects mines.

See also: miner training

A way to value a project by discounting future cash flows to today's money at a chosen rate. NPV is a calculation, not a forecast.⁶

A study may state NPV at a stated discount rate.

See also: discount rate

A private royalty paid to a prior owner as a percentage of the revenue a smelter or buyer pays, after deducting some costs.⁴

A 2 per cent NSR royalty is common on an acquired claim.

See also: royalty

National Instrument 43-101, the Canadian rule that sets how companies disclose scientific and technical information about mineral projects. It requires a Qualified Person and defined resource and reserve categories.¹⁸

A TSX-listed explorer files an NI 43-101 technical report when it first discloses a resource.

See also: Qualified Person, technical report, CIM Definition Standards

The random, short-scale variability in assays, especially in gold deposits with coarse particles, that cannot be explained by distance.⁶

A coarse-gold deposit may show high nugget effect between duplicate samples.

See also: top cut

A contract in which a buyer agrees to purchase a set share of a mine's future output, often on agreed terms.⁴

A lithium project signs an offtake with a chemical maker.

See also: concentrate

A report on exploration that a company lodges with a government survey and that becomes public after a confidentiality period.²

In Western Australia, reports in the WAMEX system become public after the confidentiality period.

See also: WAMEX, geological survey

Mining from a surface excavation in benches, usually for large, low-grade or shallow deposits.^25,34

Porphyry copper and iron ore deposits are often open pits.

See also: strip ratio, underground mining

The ongoing cost of running a mine, including labour, fuel, power, reagents and maintenance.⁶

Power and diesel are large operating costs in remote pits.

See also: capital expenditure

The company that runs a mine day to day, which may be one of several owners.⁷

The operator holds 51 per cent and runs the plant.

See also: joint venture

Rock that contains metal or minerals in high enough concentration to be mined at a profit.^1,7

Whether rock counts as ore changes with metal prices and costs.

See also: waste rock, gangue

Ore that is left behind or goes to waste during mining.⁶

Poor blast control raises ore loss.

See also: dilution

The part of a Measured or Indicated Mineral Resource that a study has shown can be mined and sold at a profit, after allowing for dilution, losses and other modifying factors. JORC calls it an Ore Reserve; Canadian and US codes call it a Mineral Reserve.^6,23

A reserve of 30 Mt at 1.0 g/t gold is usually smaller and lower grade than the resource it came from.

See also: Mineral Resource, Proved Reserve, Probable Reserve, modifying factors, pre-feasibility study

A body of rock that holds ore in a shape and size that can be mined.²⁸

The orebody is a steeply dipping lode 40 m wide.

See also: ore, lode

A gold deposit in veins and shear zones formed during mountain building, found in many greenstone belts and metamorphic terranes.¹⁵

Many Western Australian goldfields are orogenic gold.

See also: vein, greenstone belt

A sudden, violent release of solid rock and high-pressure gas, such as methane, into a mine.¹

Outbursts occur in some coal and salt mines.

See also: rock burst, methane

Soil and rock lying over an ore body that must be removed before open-pit mining.¹

Stripping overburden is the first job at a new pit.

See also: strip ratio, waste rock

Ore in which metals occur as oxides, carbonates or silicates, often near the surface after weathering. It is often treated by leaching rather than flotation.⁹

Oxide copper ore can be leached with acid.

See also: sulphide, heap leach

An ancient placer deposit that has been buried and turned to rock, such as the gold-bearing conglomerates of the Witwatersrand.¹⁵

Quartz-pebble conglomerate gold deposits are paleoplacers.

See also: placer, reef

Washing alluvial gravel in a pan so that heavy gold sinks and lighter material is washed out.⁸

A prospector pans a creek bed for colour.

See also: cradle, placer

Thickened tailings with enough solids to behave like a paste, used for backfill or surface disposal.⁷

Paste can be pumped underground as backfill.

See also: backfill, tailings

The share of the metal in a concentrate that a smelter pays for, after deductions for losses.⁶

A smelter may pay for 96 per cent of the copper in concentrate.

See also: concentrate, treatment charge

A very coarse-grained igneous rock formed from the last water-rich melt of a magma, which can hold lithium, caesium, tantalum, tin and beryllium.¹⁷

Spodumene pegmatites are the main hard-rock lithium source.

See also: spodumene, LCT pegmatite

The Pan-European Standard for Reporting of Exploration Results, Mineral Resources and Mineral Reserves, a CRIRSCO-aligned code used in Europe.⁶

A European explorer may report under PERC rather than JORC.

See also: CRIRSCO, JORC Code

Machines and devices that have been tested and approved for use where flammable gas or dust may be present.¹

Permissible lamps and motors are used in coal mines.

See also: methane

A column of unmined rock left to support the roof of an underground mine.²⁸

Pillars may be removed late in the life of a mine.

See also: room and pillar mining

A deposit of heavy minerals such as gold, tin or diamonds concentrated by water or wind in sand and gravel.^8,10

Gold in a creek bed is a placer deposit.

See also: alluvial deposit, lode

A US mining claim on loose deposits such as gold gravels.¹⁰

A placer claim covers a gravel bar.

See also: lode claim

An igneous rock with large crystals set in a fine-grained mass, associated with the intrusions that form porphyry copper deposits.⁹

Porphyry stocks are drilled for copper and gold.

See also: porphyry copper deposit

A large, low-grade deposit of copper in and around an intrusion of igneous rock, formed by hot fluids above a magma chamber. It is the main source of the world's copper.⁹

Porphyry deposits are mined in open pits in Chile, Peru and Arizona.

See also: skarn

Parts per million, a grade unit equal to one gram per tonne.²⁸

Uranium or rare earth grades are often given in ppm.

See also: g/t, grade

A comprehensive study of options for a project that settles the preferred mining method or pit design, processing route and sales plan. It is the minimum study that can support a reserve.^6,23

A PFS compares an open pit with an underground option.

See also: feasibility study, scoping study, Ore Reserve

The Canadian term for an early-stage study of project economics, similar to a scoping study. It may include Inferred resources and cannot support a reserve.²³

A junior files a PEA before it can afford a pre-feasibility study.

See also: scoping study, pre-feasibility study

The part of an Indicated (and in some cases Measured) resource that is shown to be economic after modifying factors. It carries less confidence than a Proved Reserve.^6,23

A pre-feasibility study may support only Probable Reserves.

See also: Proved Reserve, Ore Reserve, modifying factors

A forward-looking figure for tonnes, grade or metal a company plans to produce, which needs a stated basis.²⁴

ASX rules require the basis for a production target to be given.

See also: cautionary statement

Searching for mineral deposits by looking at the ground, panning streams and sampling rocks.⁴

A prospector pans a creek and follows the colour upstream.

See also: panning, exploration

The part of a Measured resource that is shown to be economic after modifying factors. It carries the highest confidence of the reserve categories.^6,23

A mature mine may have most of its near-term ore classed as Proved.

See also: Probable Reserve, Ore Reserve, Measured Resource

Iron sulphide, sometimes called fool's gold, common in many ore deposits.¹⁵

Gold is often found with pyrite.

See also: sulphide

Extracting metal using heat, such as roasting and smelting.⁷

Copper concentrates are treated pyrometallurgically.

See also: hydrometallurgy

Under NI 43-101, an engineer or geoscientist with at least five years of relevant experience who is in good standing with a professional association, and who takes responsibility for technical disclosure.^18,23

A release states that the Qualified Person has reviewed and approved the technical content.

See also: NI 43-101, Competent Person

Checks that show whether assays are reliable, using standards, blanks and duplicate samples inserted among real samples.⁶

A certified standard of known grade is inserted every 20 samples.

See also: blank

A radioactive gas that seeps from rock and decays into products that can harm the lungs, a hazard in some underground mines.¹

Radon is monitored in uranium mines.

See also: working level

One of 17 related metallic elements (the lanthanides plus scandium and yttrium) used in magnets, catalysts and electronics.¹⁶

Neodymium is a rare earth used in magnets.

See also: carbonatite, TREO

The test a mineralised body must pass to be called a Mineral Resource. It is often shown with a cut-off grade and a conceptual pit shell.^6,23

A low-grade zone deep below a pit may fail the test and be left out of the resource.

See also: Mineral Resource, cut-off grade

Comparing what the resource model predicted with what was actually mined and processed, in tonnes, grade and metal.⁶

A mine finds mined grade is 5 per cent below the model and revises its model.

See also: grade control, resource model

The share of the metal in the feed that ends up in the product, shown as a percentage. It depends on the ore and the process.^6,7

A mill with 90 per cent gold recovery turns 100 units of gold in feed into 90 in the product.

See also: metallurgical test work, head grade

The fine, alkaline residue left after bauxite is refined to alumina.²⁸

Red mud is stored in lined ponds.

See also: Bayer process, tailings

A miners' term for a gold-bearing vein or layer, used in Australia, South Africa and elsewhere.¹⁵

The Witwatersrand reefs are conglomerate layers rich in gold.

See also: lode

Purifying a metal made by smelting or leaching to market grade, by fire refining, electrolysis or chemical methods.⁷

Anode copper is refined by electrolysis.

See also: electrowinning

Gold ore that resists simple leaching because gold is locked in sulphide minerals, so it needs roasting, pressure oxidation or bio-oxidation first.⁷

Refractory ore needs pre-treatment.

See also: roasting, cyanidation

The loose, weathered cover over fresh rock, including soil and clay, which hides many deposits in Australia and Africa.³³

Aircore drilling tests the regolith for gold anomalies.

Work to restore land after mining, such as reshaping, capping and planting.²⁹

The company posts a bond for rehabilitation.

See also: mine closure

The three-dimensional block estimate of rock type, grade and tonnes built from drilling data, on which a resource statement is based.⁶

A geologist builds a block model from assays and a geological interpretation.

See also: Mineral Resource, block model

A drilling method in which compressed air carries rock chips up through the centre of the drill rods. It is faster and cheaper per metre than core drilling but gives less geological detail.⁶

RC drilling is often used to outline a zone before diamond holes.

See also: diamond drilling

Heating ore or concentrate in air to burn off sulphur and other elements, or to change the mineral.⁷

Sulphide gold concentrate may be roasted before leaching.

See also: calcine, smelting

A sudden and violent failure of overstressed rock that releases a large amount of stored energy, a hazard in deep underground mines.¹

Deep gold mines in South Africa have long dealt with rock bursts.

See also: ground control

Any device, such as a bolt, put into rock to strengthen or support it.¹

Rock bolts are rock fixtures.

See also: ground control

A uranium deposit in sandstone formed where oxidised water carrying uranium met reducing rock, leaving a crescent-shaped ore body.⁷

Roll-front deposits can be mined by in situ recovery.

See also: in situ recovery

An underground method that leaves pillars of rock to hold up the roof while rooms are mined between them.¹

Room and pillar is used in flat coal seams and some lead and copper mines.

See also: pillar

Also called RAB, a cheap shallow method in which chips return up the outside of the rods. It gives less reliable samples than aircore or RC.⁶

RAB was widely used for early-stage geochemical sampling.

A payment to the owner of the minerals, usually the state, based on the value or volume of what is produced, as opposed to a tax on profit.⁴

Western Australia received about AUD 8.6 billion in iron ore royalties in 2024-25.

See also: net smelter return royalty, ad valorem royalty

Ore as it comes out of the mine before any crushing or processing.³⁵

Run-of-mine ore is fed to the primary crusher.

See also: crushing

The US Securities and Exchange Commission rule (subpart 229.1300) that sets mining disclosure for companies registered in the US. It uses a qualified person and CRIRSCO-style resource and reserve definitions.²³

A US-registered miner files a technical report summary alongside its annual report.

See also: Qualified Person, CRIRSCO

A flexible cord with a burning core used to fire blasting caps or a black powder charge.¹

Safety fuse burns at a steady rate.

See also: detonator

A semi-autogenous grinding mill that uses the ore itself plus steel balls to break rock into fine particles.⁷

A SAG mill is the central machine in many copper concentrators.

See also: grinding, ball mill

A salt flat or dry lake basin in the Andes where brine rich in lithium and other salts lies beneath the surface.²⁶

The Atacama and Uyuni salars hold large lithium resources.

See also: brine

The weight or length of sample returned compared with what was drilled, shown as a percentage. Poor recovery makes assays less reliable.⁶

Core recovery of 98 per cent is good; 60 per cent in broken ground is a concern.

See also: drill core

The South African Code for the Reporting of Exploration Results, Mineral Resources and Mineral Reserves, one of the national codes aligned with CRIRSCO.¹⁸

A Johannesburg-listed miner reports under SAMREC.

See also: CRIRSCO, JORC Code

Weathered rock that keeps the structure of the original rock but has been changed to clay and other minerals, common in nickel laterites.³³

Saprolite is the main nickel ore zone in many laterites.

See also: laterite nickel deposit

Removing loose rock from a face or highwall so it cannot fall on workers.¹

Scaling is done after each blast.

See also: highwall, ground control

An early, low-accuracy look at whether a deposit could become a mine. It may use Inferred resources and cannot support a reserve.^6,23

A scoping study may carry a cautionary statement about the Inferred share of the plan.

See also: pre-feasibility study, preliminary economic assessment

Sorting crushed material by size over meshes or sieves.⁷

Screens remove oversize rock for re-crushing.

See also: crushing

A second connection between a conveyance and its rope so the conveyance cannot fall if the first fails.¹

Cages need a secondary safety connection.

See also: hoist

A zinc-lead-silver deposit formed when metal-rich fluids vented onto the seafloor in a sedimentary basin.²⁷

Sedex deposits supply a large share of the world's zinc and lead.

See also: volcanogenic massive sulphide deposit

A stratabound copper deposit in sedimentary rock, formed when metal-bearing brines passed through reduced layers. The Central African Copperbelt is the best known example.²⁸

The Copperbelt of Zambia and DRC is sediment-hosted.

See also: porphyry copper deposit

A vertical or steeply inclined opening from the surface used to reach underground workings, move people and raise ore.^1,5

A hoisting shaft lifts ore to the surface.

See also: adit, decline, winze

A band of rock deformed by sliding movement, which often channels fluids that deposit gold.¹⁵

Gold lies along a shear zone for several kilometres.

See also: orogenic gold deposit

A rock formed when hot fluids react with limestone or other carbonate rock next to an intrusion, which can host copper, tungsten, iron and other metals.⁹

Skarn often forms on the edge of a porphyry system.

See also: porphyry copper deposit

The molten waste, mostly silicates, that floats on top of metal or matte in a smelter.⁷

Slag is tapped from the furnace and cooled.

See also: smelting, matte

A sloping channel with riffles through which water washes gravel so heavy gold settles behind the riffles.³

Larger placer workings used long sluices.

See also: cradle, placer

A plant that smelts ore or concentrate to produce metal or an intermediate such as matte.^21,34

Copper smelters buy concentrate and charge fees.

See also: smelting, treatment charge

Heating ore or concentrate with fluxes to melt it and separate metal or matte from slag.^21,34

Copper concentrate is smelted into matte.

See also: matte, slag, smelter

Collecting soil at set spacing and analysing it for metals to detect buried mineralisation.⁶

Lines of soil samples every 50 m trace a gold trend.

See also: geochemistry, anomaly

A way to move a metal from a dilute leach solution into an organic liquid, then back into a clean, strong solution.²⁶

Solvent extraction purifies and concentrates copper solution.

See also: SX-EW

A method that uses vibration to advance a core barrel, used in soft sediments, clays and unconsolidated ground.⁶

Sonic rigs sample lithium clay or sand deposits.

See also: diamond drilling

Zinc sulphide, the main ore mineral of zinc.²⁷

Sphalerite often occurs with galena.

See also: galena

A lithium aluminium silicate mineral that is the main ore mineral in hard-rock lithium mines.¹⁷

Spodumene concentrate is sold to chemical plants that make lithium compounds.

See also: pegmatite, lithium carbonate equivalent

The current market price for immediate delivery of a commodity.⁷

Gold's spot price is quoted per troy ounce.

A mill with heavy vertical pestles, called stamps, that rise and drop to crush ore into sand for gold or tin extraction.⁵

Stamps crushed Cornish tin ore before dressing.

See also: buddle

A reference sample of certified grade inserted among drill samples to check that the laboratory returns the right answer.⁶

A laboratory result far from the certified value flags a problem.

See also: quality control, blank

A pile of ore or waste kept on the surface for later treatment or blending.⁷

Low-grade stockpiles may be processed late in mine life.

See also: run-of-mine

A network of small veins in rock, giving bulk-mineable ore in places like porphyry deposits.¹²

A stockwork of quartz veins carries molybdenum.

See also: vein

An underground excavation from which ore has been or is being removed.^1,5

Miners blast a stope from the bottom up.

See also: stoping, backfill

The process of mining ore from stopes underground.⁵

Cut and fill stoping is used in narrow veins.

See also: stope

A deal in which an investor pays money up front for the right to buy a share of a mine's future metal output at a low fixed price.⁴

A mine sells a share of its silver by-product under a stream.

See also: royalty, by-product

The compass direction of a horizontal line on a tilted rock layer or vein.⁶

A vein striking north-south dips to the east.

See also: dip

The tonnes of waste that must be removed to mine one tonne of ore in an open pit.⁷

A strip ratio of 3:1 means three tonnes of waste for each tonne of ore.

See also: overburden

A mineral in which metal is combined with sulphur, such as pyrite (iron), chalcopyrite (copper), galena (lead) and sphalerite (zinc).⁹

Copper from sulphide ore is usually recovered by flotation.

See also: oxide ore

The WA rule under which exploration reports held by the department for five years may be released to the public.²

Reports held for five years are listed for release each year.

See also: WAMEX, open file report

The process in which weathering dissolves metals near the surface and redeposits them lower down, forming a richer zone.⁹

Supergene enrichment gave many porphyry copper deposits a rich chalcocite blanket.

See also: porphyry copper deposit

Solvent extraction and electrowinning: leach solution is concentrated by an organic solvent, then copper is plated from the clean solution as cathode.²⁶

SX-EW turns heap leach liquor into copper cathode with no smelter.

See also: solvent extraction, electrowinning, heap leach

The grade of the waste stream leaving the plant, which shows how much metal was left behind.⁶

A tail grade of 0.1 g/t from a 1.2 g/t head means most gold was recovered.

See also: head grade, tailings

The fine waste left after valuable minerals are removed from ore at a processing plant, usually pumped as slurry to a storage facility.^1,3

A tailings facility holds waste from a copper concentrator.

See also: tailings dam

An embankment built to hold tailings and water, sometimes raised in stages as more waste is added. Its failure can release large volumes of slurry.¹¹

Safety reviews check tailings dams for stability.

See also: tailings

The long document a Canadian-listed company files to support material disclosure about a mineral project, following Form 43-101F1.¹⁸

A first resource estimate on SEDAR+ comes with a technical report.

See also: NI 43-101, Qualified Person

The Australian term for a granted right to explore or mine an area, such as an exploration licence or mining lease.²

A company holds three tenements covering a greenstone belt.

See also: mining lease, exploration licence

A large tank in which solids settle out of a slurry so clear water can be reused.²⁹

Tailings pass through a thickener to recover water.

See also: dewatering

The ancient practice of washing tin from stream gravels, mainly in Cornwall and Devon.⁵

Streamers washed cassiterite from the valleys of Dartmoor and Cornwall.

See also: alluvial deposit, cassiterite

A cap applied to very high individual assays so that one extreme value does not distort the average grade of an interval or a block.⁶

Capping 120 g/t gold assays at 40 g/t reduces the average of a high-grade intercept.

See also: nugget effect, intercept

A passage or way regularly used and marked for people to go from one place to another.¹

Travelways must be kept clear.

See also: escapeway

A fee a smelter charges a miner to treat concentrate, usually per tonne of concentrate.⁷

Treatment and refining charges are set in annual benchmark talks.

See also: smelter, concentrate

Total rare earth oxides, the combined content of all rare earth elements in a sample, expressed as oxide.¹⁶

A deposit may grade 4 per cent TREO.

See also: rare earth element

A miner who worked part of a mine on contract and was paid a share of the value of the ore raised.⁵

Tributers bid for pitches at a monthly setting.

See also: tutworker

The unit used to price gold, silver and platinum group metals. One troy ounce is about 31.1035 grams.⁷

10 million tonnes at 1.5 g/t holds about 482,000 troy ounces.

See also: g/t, contained metal

The real thickness of a mineralised zone measured at right angles to its contacts. It is less than the downhole width unless the hole crosses the zone at 90 degrees.⁶

A 12 m downhole intercept may be only 7 m in true width.

See also: downhole width, dip

A Cornish miner who worked on a task basis, paid by the amount of rock removed, such as shaft sinking.⁵

Tutwork was paid by the fathom.

See also: tributer

Igneous rock very rich in iron and magnesium, which hosts nickel, chromium and platinum group deposits.³²

Komatiite lavas are ultramafic.

See also: magmatic sulphide deposit

A type of uranium deposit found near the contact between old basement rock and younger sandstone, such as in Saskatchewan's Athabasca Basin.⁷

Athabasca deposits are among the highest-grade uranium in the world.

See also: roll-front uranium

Mining through shafts, declines and tunnels to reach ore too deep or too narrow for an open pit.^1,7

Narrow gold lodes are mined from underground.

See also: stope, shaft, decline

A US lode or placer claim for which no patent has been issued, so the land stays federal.¹⁰

Most US claims are unpatented.

See also: mineral patent

A sheet-like body of minerals deposited by hot fluids in a crack in rock.¹⁵

Quartz veins carry gold at many orogenic deposits.

See also: lode

Moving fresh air through underground workings to supply oxygen and dilute dust, fumes and gas.¹

Main and booster fans drive ventilation.

See also: main fan, auxiliary fan

A deposit of copper, zinc, lead and other metals that formed on or below the seafloor from hot, metal-rich fluids around volcanic activity.¹⁹

VMS deposits are mined in Canada, Sweden and Spain.

See also: sedex deposit

The Western Australian Mineral Exploration reports database, where open-file company exploration reports can be searched and downloaded free.²

A prospector searches WAMEX for old drilling around a tenement.

See also: open file report, Sunset Clause

Rock removed to reach ore that does not carry enough metal to be processed.^1,6

Waste rock is piled in a dump beside the pit.

See also: overburden, strip ratio

Applying water through the drill steel to the bottom of the hole to keep dust down.¹

Wet drilling protects drillers.

A horse-powered or steam-powered winding gear used to raise ore and lower men in a shaft.⁵

A whim engine hauled ore at a small mine.

A shaft sunk from one level underground to a lower level without reaching the surface.¹

Miners sank a winze to follow the lode downward.

See also: shaft, adit

The gold-bearing quartz-pebble conglomerates of the Witwatersrand Basin in South Africa, the largest gold resource ever mined.¹⁵

Witwatersrand reefs were worked from 1886.

See also: paleoplacer, reef

A measure of radon decay product concentration in air, used to limit exposure underground.¹

Uranium and some other mines monitor working levels.

See also: radon