calcination
Heating a mineral strongly enough to drive off gases — often water vapour or carbon dioxide — without actually melting it.
Tecnicamente: Calcination is a thermal treatment carried out below the fusion point of the material, with the primary purpose of driving off volatile components such as chemically bound water, carbon dioxide or sulfur dioxide, thereby transforming the feed into a more reactive or chemically altered solid product. It is routinely confused with roasting: the distinction is that calcination targets decomposition or dehydration rather than oxidation of a sulfide or other reactive species. In the Bayer process, for example, aluminium hydroxide is calcined to produce anhydrous alumina.
Processing
capex
The large, upfront sums of money spent to build a mine or processing plant before it starts producing anything.
Tecnicamente: Capital expenditure, universally abbreviated to capex in the mining industry, refers to spending on physical assets required to bring a project into production or to sustain and expand an existing operation. In project evaluation it is divided into initial capex, covering construction to first production, and sustaining capex, covering ongoing asset replacement and expansion over the mine life. The accuracy of capex estimates improves through the study hierarchy from PEA to feasibility study; overruns in capex relative to feasibility-study estimates are one of the most common causes of project economics deteriorating between sanction and commissioning.
Markets
carbonatite
A rare type of volcanic rock made mostly of carbonate minerals — the same family as limestone — rather than the silicate minerals found in ordinary igneous rocks. Some carbonatites are important sources of rare-earth elements and niobium.
Tecnicamente: Carbonatite is an igneous rock, intrusive or extrusive, containing more than fifty percent carbonate minerals by volume, typically calcite, dolomite, or ankerite. It is genetically distinct from carbonate sedimentary rocks and from carbonated hydrothermal veins. Carbonatites are economically significant as hosts for niobium, rare-earth elements, phosphate, fluorite, and occasionally copper, and they are often associated with alkaline silicate intrusions in continental rift settings. The distinction from a marble or a hydrothermal carbonate vein rests on demonstrating an igneous origin through geochemistry and field relationships.
Geology
care and maintenance
Care and maintenance is when a mine has stopped producing but has not been permanently closed. The site is kept in a safe, working condition so that mining could start again if conditions improve.
Tecnicamente: Care and maintenance describes an operational status in which a mine has suspended production but maintains sufficient infrastructure, staffing and monitoring to preserve the physical and environmental integrity of the site and to allow restart without full recommissioning. It differs from closure in that no commitment to permanent cessation has been made and rehabilitation obligations are deferred. The status is typically adopted when commodity prices fall below the cash cost of production, when a key permit lapses, or when a resource owner is seeking to divest the asset; holding costs during care and maintenance are materially lower than full operating costs but are not zero.
Mining
cathode
The clean sheet of metal that pure metal grows onto during electrorefining or electrowinning. At the end of the process the cathode is the finished, high-purity product.
Tecnicamente: In electrometallurgy, the cathode is the negatively charged electrode onto which metal ions from the electrolyte are reduced and deposited as solid metal. In copper production the term 'cathode' is used both for the electrode itself during the process and for the flat, high-purity copper product that is sold after it is stripped from the starting sheet. Cathode copper is the standard tradeable form of refined copper and must meet published purity specifications to qualify for exchange-registered delivery; it is sometimes confused with the anode, which is the dissolving or oxidising electrode carrying the opposite charge.
Processing
cathode active material
The powder inside a battery's positive end that actually stores and releases electrical energy by holding onto lithium ions when the battery is charged.
Tecnicamente: Cathode active material (CAM) is the lithium-bearing oxide or phosphate compound that forms the electrochemically active component of the positive electrode in a lithium-ion cell, accepting and releasing lithium ions during discharge and charge respectively. Common CAM chemistries include lithium nickel manganese cobalt oxide (NMC), lithium nickel cobalt aluminium oxide (NCA), and lithium iron phosphate (LFP), each with different trade-offs in energy density, thermal stability, and cycle life. CAM is distinct from the precursor cathode active material (PCAM) from which it is synthesised and from the finished electrode, which also contains binder, conductive carbon, and a current collector.
Processing
circularity
Designing systems so that materials keep being used again and again, rather than being thrown away after a single use — like a bottle that is refilled hundreds of times instead of discarded.
Tecnicamente: An approach to material flows in which the useful life of materials is extended through reuse, remanufacturing and recycling, reducing dependence on primary extraction. In minerals and metals analysis, circularity is measured in terms of collection rates, recycling rates and the proportion of secondary material that re-enters productive use at equivalent quality to primary material. It is important to distinguish circularity from recycling alone: circularity is a broader concept that encompasses design for disassembly, product life extension and closed-loop industrial systems, of which recycling is one component.
Markets
co-product
When a mine or factory produces two or more things at the same time and each one is important enough to help justify running the whole operation.
Tecnicamente: A co-product is a material recovered alongside another from the same ore body or process stream, where both contribute materially to the economic viability of the operation. Unlike a by-product, a co-product receives its own share of joint production costs rather than being treated as a credit. The boundary between co-product and by-product is contested and varies by accounting convention; in practice the distinction often turns on whether removing the secondary material would make the operation uneconomic.
Materials
comminution
Comminution means breaking rock into smaller and smaller pieces—first by crushing big lumps, then by grinding those pieces into a fine powder—so that the useful mineral grains become free from the surrounding rock.
Tecnicamente: Comminution is the collective term for all size-reduction stages in mineral processing, spanning primary crushing through to fine grinding, and its purpose is the liberation of valuable mineral particles from the host rock matrix at a particle size fine enough for effective separation. It typically accounts for the largest share of a concentrator's energy consumption, which makes comminution circuit design and efficiency central concerns in both plant economics and environmental assessment. The term encompasses crushing (above roughly a few millimetres product size) and grinding (below that threshold), and should be distinguished from classification, which is the separation of particles by size rather than their reduction—though the two operations are almost always conducted in close circuit with one another.
Mining
companion metal
A metal that hides inside the ore of a different, more common metal and can only be collected when that common metal is being processed.
Tecnicamente: A companion metal is one that occurs in ore principally as a trace constituent of another metal's mineral host rather than in economically minable deposits of its own, meaning its supply is structurally tied to the production decisions made for the host metal. Indium in zinc ores and tellurium in copper anode slimes are typical examples. Because a companion metal cannot be ramped up independently, its supply responds poorly to price signals, making it particularly susceptible to shortfalls when demand grows faster than host-metal production.
Materials
concentrate
The valuable mineral-rich material collected after processing ore. Think of it as the useful part that has been separated from most of the waste rock, ready for the next stage of treatment.
Tecnicamente: A concentrate is the product of a beneficiation step—commonly flotation or gravity separation—in which the grade of the target mineral or metal has been substantially raised relative to the run-of-mine ore, and most gangue has been discarded as tailings. Concentrates are defined by their contained metal grade and penalty element levels, which govern their commercial value and smelter treatment charges. The term is distinct from 'ore': ore refers to mineralised rock in the ground or as mined, while concentrate is an intermediate, processed product.
Processing
concentrator
A concentrator is a processing plant that takes crushed and ground ore and separates out the valuable mineral, producing a concentrate—a much smaller, richer portion—while the unwanted material goes to a waste pile called tailings.
Tecnicamente: A concentrator is a facility or integrated circuit of equipment whose primary function is physical or physico-chemical separation of valuable minerals from gangue, raising the grade of the target mineral to levels acceptable for smelting or hydrometallurgical treatment. The defining output is a concentrate—a product in which the valuable mineral is substantially enriched relative to the feed ore—alongside a tailings stream that contains the discarded gangue and process water. The term is sometimes used as a synonym for 'mill', but a concentrator is more precisely defined by its separation objective: a mill may perform grinding without achieving a saleable concentrate (for instance, when feeding a heap-leach pad), whereas a concentrator always produces one.
Mining
conflict mineral
A mineral that has been mined in a war zone and sold to help fund the fighting, in the same way that 'blood diamonds' became a well-known example.
Tecnicamente: A mineral extracted in a region of armed conflict where the proceeds of trade are reasonably understood to finance or benefit armed groups, whether state or non-state actors. The term carries a specific legal meaning under certain national legislations and due-diligence frameworks, which typically enumerate particular minerals and regions of concern rather than applying the category universally. It is important not to conflate the term with artisanal or small-scale mining in general, or with minerals produced in politically unstable regions that are not conflict-affected in the legal sense.
Markets
contained metal
The actual amount of useful metal sitting inside a quantity of ore or concentrate, not counting the rock, water or other waste wrapped around it.
Tecnicamente: Contained metal is the mass of a target metal element present in a stated quantity of ore, concentrate or other material, calculated by multiplying the total material mass by the assayed grade of that element. It is expressed in units of the pure metal, not the compound, unless stated otherwise. The term is important because commercial transactions and resource statements can report either contained metal or the weight of the physical material shipped; confusing the two — particularly when dealing with concentrates that may be only a fraction pure — is a common source of error in supply chain accounting.
Materials
conversion
A processing step that changes a material from one chemical form into another so it is ready for the next stage — like turning a metal ore into a gas that can be sorted by weight.
Tecnicamente: In the nuclear fuel cycle, conversion refers specifically to the chemical process by which uranium oxide concentrate (yellowcake) is purified and reacted to form uranium hexafluoride (UF₆), the gaseous compound required as feed for enrichment. Outside the nuclear industry the term is used more broadly for any stage that transforms a material into a chemically distinct intermediate suited to downstream processing, such as the conversion of ilmenite to synthetic rutile or titanium tetrachloride. The nuclear-fuel sense is the most precisely delimited and is the one most often intended when the word appears alongside 'enrichment' and 'yellowcake' without further qualification.
Processing
core sample
A core sample is a long cylinder of rock drilled out of the ground whole, like using a hollow cookie-cutter through layers of cake, so geologists can see the rock exactly as it sits underground.
Tecnicamente: A core sample is a continuous cylindrical section of rock recovered by a diamond or other rotary drill bit fitted with an annular cutting face, which preserves the original stratigraphy, structure, and mineralisation relationships along the drill path. Core recovery percentage — the proportion of the drilled interval actually retrieved — is recorded because incomplete recovery can bias grade estimates, particularly in friable or broken ground. Core differs from drill chips or reverse-circulation cuttings in that it retains orientation and intact fabric, making it the preferred sample type for structural logging and geometallurgical testwork.
Geology
cost curve
A chart that lines up all the world's mines for one commodity from cheapest to most expensive, so you can see which ones would shut down first if the price fell.
Tecnicamente: A cost curve ranks producing operations by their unit cost of production — typically C1 cash cost or AISC — plotted against their cumulative output, forming a step function that rises from left to right. The curve's shape reveals the industry's cost structure: a flat curve indicates producers are tightly clustered in cost, while a steep right-hand tail shows a small number of high-cost operations that are marginal at prevailing prices. The curve is widely used to assess where the price floor might settle in a downturn, on the assumption that producers to the right of the prevailing price are candidates for curtailment.
Markets
critical mineral
A mineral that a country or industry depends on heavily but might struggle to keep getting, either because it only comes from a few places or because there is no easy substitute for it.
Tecnicamente: A mineral is designated critical when two conditions coincide: supply is concentrated enough that a disruption is plausible, and there is no ready substitute for the material's function in key applications. Criticality is not a fixed property of the mineral itself; it is a relationship between supply geography, demand concentration and available alternatives, so a mineral may appear on one country's critical list but not another's.
Materials
current collector
A thin metal sheet inside a battery that gathers the electricity produced by the active materials and carries it to the battery's terminals — like a bus collecting passengers and delivering them to the station.
Tecnicamente: A current collector is a conductive substrate — typically a metal foil — onto which the active electrode material is coated or deposited, serving to gather electrons from across the electrode surface and conduct them with minimal resistance to the external circuit. In lithium-ion batteries, copper foil is conventionally used for the anode side and aluminium foil for the cathode side, the choice being governed by electrochemical stability at the respective operating potentials. Current collectors are sometimes overlooked in materials discussions because they are not electrochemically active, but their conductivity, thickness, and corrosion resistance directly affect cell efficiency and the overall mass loading of the finished cell.
Materials
cut-off grade
The lowest grade of rock that is still worth processing. Rock above the cut-off goes to the mill; rock below it is left behind or sent to the waste dump.
Tecnicamente: Cut-off grade is the minimum grade at which a unit of rock — a block, bench, or development heading — generates sufficient revenue to cover the cost of mining, processing, and selling. It determines the boundary between ore and waste and therefore controls both the size and the average grade of the reported resource or reserve. Because it is derived from cost and price assumptions, cut-off grade changes with commodity prices, exchange rates, and processing recoveries, which means the economic boundary of an orebody is not fixed.
Geology