AISC
A way of adding up almost everything it costs to produce one unit of a metal — not just the day-to-day running costs but also the spending needed to keep the mine going into the future.
Técnicamente: All-In Sustaining Cost is a metric developed to give a fuller picture of the cash cost of production than simple cash-cost or C1-cost figures. It adds sustaining capital expenditure, corporate general and administrative costs, and often reclamation accruals to the direct operating cost, but excludes expansion capital and financing costs. AISC is most widely used in gold and silver reporting, where it was formalised by the World Gold Council, though the precise scope of inclusions varies between companies, which limits strict cross-company comparison.
Markets
acid mine drainage
Acid mine drainage is water that turns acidic after flowing through broken rock that contains certain sulfur minerals. This acidic water can carry dissolved metals into rivers and streams, harming the environment.
Técnicamente: Acid mine drainage (AMD) is the low-pH, metal-laden water produced when sulfide minerals — most commonly pyrite — are exposed to oxygen and water, generating sulfuric acid through a combination of chemical and bacterially mediated reactions. AMD can arise from active workings, waste-rock dumps, tailings facilities or abandoned workings, and its generation may continue for decades or centuries after mining ceases. It is distinguished from neutral mine drainage in that the acid load exceeds the neutralising capacity of the surrounding rock and water, enabling the mobilisation of iron, manganese and a range of heavy metals at concentrations that can be acutely toxic to aquatic systems.
Mining
adit
A horizontal tunnel driven directly into the side of a hill or mountain to reach ore underground, so that water and broken rock can drain or roll out naturally without being lifted.
Técnicamente: A horizontal or near-horizontal entry driven from the surface into a hillside or cliff face to provide access to underground workings, with the primary advantage that it allows natural gravity drainage of groundwater and, in some configurations, gravity tramming of ore. An adit differs from a decline in that it is essentially flat rather than inclined, and it differs from a shaft in being horizontal rather than vertical. In hilly or mountainous terrain, adits can give access to multiple levels if the topography permits entry points at different elevations. The term is sometimes loosely applied to any horizontal underground opening, but in precise usage it refers specifically to an opening that intersects the surface.
Mining
anode
The impure block of metal that slowly dissolves away during electrorefining. Electricity pulls metal atoms off it and deposits them, in purified form, onto the cathode on the other side of the tank.
Técnicamente: In electrorefining, the anode is the positively charged electrode, cast from blister or fire-refined copper, that undergoes oxidative dissolution as the current drives metal ions into solution. Its composition determines which impurities accumulate in the electrolyte and which collect as anode slime beneath or around it. The term is also used in electrowinning, but there the anode is an inert or dimensionally stable electrode that does not dissolve; confusing the two contexts matters because anode behaviour and anode slime generation are specific to electrorefining only.
Processing
anode slime
A muddy residue that collects under the dissolving anode during electrorefining. It contains impurities and sometimes valuable materials such as silver and gold that did not dissolve into the liquid.
Técnicamente: Anode slime is the solid residue that accumulates at the base of the anode or on the cell floor during copper electrorefining, composed of anode constituents that are insoluble under the operating conditions of the electrolyte—typically selenium, tellurium, lead sulfate, and the precious metals silver, gold, and platinum-group elements. Recovery of these by-products from anode slime is often an economically significant part of a copper refinery's operation. The composition and quantity of anode slime are direct functions of the anode chemistry, making anode quality control important for by-product recovery planning.
Processing
anomaly
An anomaly is a spot where a measurement — such as the strength of a magnetic field or the amount of a metal in soil — is noticeably different from the surroundings, suggesting something unusual might lie underground.
Técnicamente: In exploration geology, an anomaly is a statistically significant departure from the local or regional background value of a measured parameter, whether geochemical, geophysical, or remote-sensing derived, and it forms the basis for prioritising drill targets. Not all anomalies reflect economic mineralisation; many result from barren lithological contrasts, instrument artefacts, or surficial contamination, which is why anomaly follow-up always involves additional lines of evidence before drilling is committed. The term should be qualified by its type and the method that detected it — for example, a soil geochemical anomaly differs fundamentally in its implications from a magnetic anomaly even if both occur in the same area.
Geology
apparent consumption
An estimate of how much of a material a country uses, calculated from production and trade figures rather than from measuring what each factory actually consumes.
Técnicamente: Apparent consumption is calculated as domestic primary production plus imports minus exports, with an adjustment for changes in reported inventory levels where such data are available. It is described as 'apparent' because it is derived from supply-side statistics rather than measured at the point of end use, meaning it includes any unrecorded stockbuilding or drawdown. Apparent consumption is the standard proxy for demand in national and global commodity balances and feeds directly into the calculation of net import reliance. It can diverge significantly from true consumption when stock changes are large, unreported, or estimated with low accuracy.
Markets
artisanal mining
Artisanal mining is small-scale mining done by individuals or small groups using simple hand tools rather than large machinery. It is common in many parts of the world and is how some communities make a living.
Técnicamente: Artisanal and small-scale mining (ASM) refers to informal or semi-formal mining conducted by individuals, families or small cooperatives using predominantly manual methods and limited mechanisation, typically without the permits, capital investment or technical infrastructure of industrial operations. The term encompasses a wide spectrum of formality: some ASM operators work within legal frameworks, others in de facto legal grey areas, and others outside any regulatory system entirely. ASM is distinguished from small-scale industrial mining chiefly by the absence of systematic geological assessment, engineered mine design and formal employment structures, rather than by any fixed threshold of tonnage or output.
Mining
assay
An assay is a chemical test that measures exactly how much of a valuable mineral or metal is present in a piece of rock, the way a cook might weigh out exactly how much sugar is in a recipe.
Técnicamente: An assay is a quantitative analytical procedure applied to a rock, soil, or water sample to determine the concentration of one or more elements or minerals, reported in units such as grams per tonne or percentage by mass. In resource estimation, assay results are the primary input to grade calculations and must be traceable to certified reference materials and blanks to be defensible. Assay is sometimes loosely used to mean the result itself rather than the procedure; technical reports treat these as distinct.
Geology
assessed price
A price that a specialist reporting agency works out by collecting information about real deals and published offers, then publishing its best estimate of what the commodity is worth that day.
Técnicamente: An assessed price is produced by a price reporting agency (PRA) — such as Fastmarkets, Platts or Argus — using a defined methodology that aggregates transaction data, bids, offers and broker quotes over a fixed assessment window, typically the end of a trading day. Because many commodity markets are opaque and transactions infrequent, the assessment reflects the PRA's methodology as much as the raw market; different agencies applying different criteria to the same market can publish different numbers. Assessed prices are routinely embedded in physical supply contracts as the pricing reference, which makes the methodology and its governance commercially significant. They are distinct from exchange-settled prices, which derive from standardised, centrally cleared contracts.
Markets
autoclave
A sealed, pressurised vessel that lets water be kept much hotter than its normal boiling point, so that reactions happen faster or at all.
Técnicamente: In metallurgical processing an autoclave is a pressure vessel in which aqueous leaching is conducted at elevated temperature and partial pressure of oxygen or steam, allowing solution temperatures well above the atmospheric boiling point of water and enabling oxidation or dissolution reactions that are thermodynamically or kinetically impractical at ambient pressure. The term describes the vessel itself, though it is commonly used as shorthand for the pressure-leach operation performed within it. It should not be conflated with a simple heated leach tank; the defining characteristic is that the system operates above ambient pressure, which fundamentally alters both the chemistry and the engineering requirements.
Processing