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The process of binding the fine particles in crushed ore to each other or to coarser particles, using water, acid or other additives, to produce a permeable feedstock for heap leaching.


Modification of the chemistry and mineralogy of rocks by the passage of hydrothermal fluids.


An inverted U-shaped fold with the oldest rocks in the centre.


A geological era lasting from about 3800 to 2500 million years ago.


The chemical symbol for gold.


see grinding



The older igneous and metamorphic rocks which underlie any younger, largely unmetamorphosed sedimentary or volcanic rocks in an area.


Banded iron formation. A distinctive type of rock often found in greenstone belts, consisting of repeated thin layers of iron oxides alternating with bands of iron-poor shale and chert.

Bottle roll

Bench-scale leaching test in which samples are placed in plastic bottles with the leaching reagent and agitated continuously by rolling on rotating rollers. The method is most frequently used for cyanide leaching of gold or sulphuric acid leaching of base metals.

Block model

A three-dimensional mathematical model of a mineral deposit in which the ore body is divided into uniformly-sized blocks and the grade of each block is estimated from the drillhole sample data using some kind of interpolation technique, such as Kriging.


A rock composed of coarse angular fragments.


Superficial Gravels cemented by calcium carbonate.


Minerals containing the carbonate anion (-CO3), or sedimentary rocks composed of calcium or magnesium carbonate minerals.

Central African Copperbelt

A giant metallogenic province extending for about 700km though the Democratic Republic of Congo (DRC) and Zambia. The Copperbelt lies within the Lufilian Arc, a fold belt formed by tectonic compression of the Neoproterozoic Katangan sedimentary basin between the Congo and Kalahari Cratons. The Copperbelt contains many large, high grade sediment-hosted, mostly stratiform copper ore deposits, almost within the Roan Group. The Copperbelt has a global resource of almost 200Mt of copper metal and contains two of the world’s ten biggest copper deposits. Many of the deposits also contain high cobalt concentrations, with the Copperbelt accounting for around 40% of the world’s cobalt reserves, and some deposits also hold significant uranium resources. Lead, zinc and iron deposits are also found.


The chemical symbol for cobalt.


A sedimentary rock consisting of rounded or sub rounded fragments larger than 2 mm.


An intermediate product between run of mine ore and metal, into which metal ore minerals have been concentrated, usually by a physical process such as froth flotation or density separation.


The chemical symbol for copper.

Cut-off grade

The grade used to separate ore and waste such that only material classified as ore will be treated in order to recover the economic metal or mineral of interest.


The chemical symbol for Chromium.


Geological Period from 136 million years to 64 million years.

Diamond drilling

Drilling using a water-cooled rotating hollow diamond-tipped bit, cutting a core through the rock which can be brought to the surface by a core barrel.


A member of the Katangan Supergroup, described from the DRC and correlated with the Upper Roan of Zambia.


(Electromagnetics) A geophysical prospecting method that uses electromagnetic impulse excitation to investigate the subsurface.


equivalent nickel, a shorthand means of including the value of by-product cobalt in the average grade and contained metal tonnage of a deposit, calculated as eNi = Ni + (Co x 1.32), based on US$10/lb Ni and US$17/lb Co, with recoveries of 90% for Ni and 70% for Co.

Exploration Target

An estimate of a potential target size and type reported according to paragraph 18 of the JORC code.

Feasibility study

A study of the economic viability of the mining and production of base or precious metals or other minerals in such form and containing such detail as is customarily required by a bank or other financial institution engaged in mining project finance to enable it to determine whether to finance the development of a commercial mining operation.


A method of separating ore mineral grains from other materials using surfactant chemicals to entice them to adhere to bubbles in an aerated mixture of crushed ore in water, allowing them to be skimmed from the surface of the mixture.

Foot Wall

The name given to the host rock of an ore deposit that is physically below the ore deposit


A coarse grained basic igneous rock composed of feldspar and minerals rich in iron and magnesium.

Gamma Ray Spectrometer

An instrument which measures the quantities and energies of gamma rays produced by the radioactive decay of unstable isotopes and is usually employed in ground or airborne surveys to map variations in concentration of three naturally occurring radioactive elements (potassium, uranium and thorium) within the uppermost metre of the Earth.


The investigation of the chemistry of rocks.. In mineral exploration, geochemistry is usually applied to the search for mineral deposits by sampling and analysing the soils, stream sediments or rock outcrops of an area.


The investigation of the rocks of an area by measuring variations in their physical properties, especially their magnetism, radioactivity, density and electrical properties.


A branch of statistics focusing on spatial datasets, with a collection of numerical and mathematical techniques dealing with the characterization of spatial phenomena.


The intensely oxidized, weathered or decomposed uppermost and exposed part of an ore deposit or mineral vein.


An iron bearing hydroxide mineral found in soil and other low-temperature environments.


A geophysical method which maps variations in the Earth’s gravity field caused by the sub-surface disposition of rocks of varying densities.


The tenor or concentration by weight of a metal in a mineral deposit or ore


Grams per tonne


A coarse grained igneous rock high in silica, which usually forms large intrusive masses.

Greenstone belt

Zones of metavolcanic sequences with associated sedimentary rocks that occur within Archaean and Proterozoic cratons between granite and gneiss bodies. The belts often contain ore deposits of gold, silver, copper, zinc and lead.


The process of pulverising ore before treatment to extract the valuable components. Usually, crushed ore is placed together with a grinding medium such as steel balls in a cylindrical mill with its axis close to horizontal, and tumbled by revolving the mill.  In the case of autogenous grinding, no griding medium is added but the coarser part of the ore grinds itself and the finer part; in semiautogenous mills, only a small quantity of grinding medium is added.

Hanging Wall

The name given to the host rock of an ore deposit that is physically above the ore deposit.

Heap leaching

A process to extract metals from ore, in which the mined ore is crushed and heaped onto a sculpted impermeable plastic- or clay-lined leach pad and irrigated with a leaching agent which percolates through the heap and leaches out the metals. When the “pregnant” metal-bearing leach solution reaches the impermeable base membrane, the sculpting directs it to canals from which it is collected and processed to precipitate out the valuable metals.

High pressure acid leaching

(HPAL) a process to extract metals from mined ore, which is crushed and ground to powder, then leached with sulphuric acid in an autoclave at high temperature and pressure, typically 250ºC and 4000kPa for nickel and cobalt. The leaching is rapid, typically 30 – 60 minutes to achieve extractions of 92-96% of the contained nickel and cobalt. Acid consumption is lower than with other leach methods due to the precipitation of hematite in the autoclave but capital cost and energy costs are high.


Pertaining to the passage of hot water through rocks. Important in mineral exploration because hot, often superheated, water can dissolve and carry metals, and later precipitate them to form mineral deposits.

Igneous rocks

One of the three main rock types (the others being sedimentary and metamorphic rock), igneous rocks are formed by cooling and solidification of molten rock (magma). They may form with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.

Indicated Resource

A category of Mineral Resource of higher confidence than an Inferred Resource, the estimation of which is prescribed by the JORC Code. This is the minimum level of resource classification required for Ore Reserve estimation under the JORC Code.

Inferred Resource

A category of Mineral Resource the estimation of which is prescribed by the JORC Code. Inferred Resources cannot be used as a basis for Ore Reserve estimation.


An area of older rocks completely surrounded by younger rocks.


Iron-oxide-copper-gold. A class of mineral deposits characterised by extensive hydrothermal alteration and mineralisation associated with certain granites and other intrusive rocks.


Induced Polarisation. A geophysical prospecting method which measures the induction of electrical charge on the surfaces of conducting mineral grains such as metal ores, within the Earth.


Australasian Code for the Reporting of Exploration Results, Mineral Resources and Ore Reserves (Joint Ore Reserves Committee,


A copper-gold deposit near Sulwezi in the Zambian Copperbelt, which has several characteristics setting it apart from other deposits of the belt. It is being mined by First Quantum.


Upper Carboniferous to Lower Jurassic sediments and lava flows of considerable extent in Southern and Central Africa.


A supergroup of rocks dating from the Neoproterozoic which is widespread across central Africa and contains the Central African Copperbelt.


A class of volcanic pipes, dykes and craters which result from explosive eruption of rocks derived from very deep sources, driven by violent de-gassing. Kimberlites are the principal source of diamonds, which are formed at the high pressures at very great depth and are carried to the surface intact by the very fast ascent and cooling of these eruptions.


A South African term for a small hill with sparse vegetation, steep rocky slopes and large boulders, generally of granite or gneiss, which may occur in isolation or in groups in savannah or woodland.


A member of the Katangan Supergroup, notable for containing two layers of glacial deposits, the Grand Conglomerat and the Petit Conglomerat, which are believed to have been deposited during “Snowball Earth”  events.


A class of methods of estimating mathematically the distribution of a metal in three dimensions within the earth, together with the confidence of the estimate


A surface layer, up to 100m thick, produced when water-soluble elements and silica are progressively removed from rocks by the weathering process, leaving residual material rich in the less mobile elements. Their chemistry depends on the original rocks, but laterites are often rich in iron and aluminium, and can contain significant nickel and cobalt. Laterites usually form in humid tropical conditions.


The extraction of metals from pulverised ore by dissolving them in a chemical solution, especially the extraction of gold using sodium cyanide.


An extremely fine-grained magnesium mineral of the Serpentine Group

Lower Roan

The earliest member of the Katangan Supergroup, believed to be around 850 million years in age, which contains most of the sediment-hosted deposits of the Central African Copperbelt.

Manganese wad

An old mining term for any black rock rich in manganese oxide or hydroxide minerals, in the oxidized zone of various ore deposits. It is typically associated with various iron oxides and may contain significant concentrations of any other metals present in the system, notably Ni, Co, Fe, Al or Ba.

Measured Resource

A category of Mineral Resource of higher confidence than an Indicated Resource, the estimation of which is prescribed by the JORC Code


A statistical estimate of the central tendency of a set of values, with half the values being more than and half being less than the median value.


A geological era lasting from 1600 to 1000 million years ago.


Relating to the study of the extraction, processing and properties of metals and their ores

Metamorphic rocks

Rocks resulting from the transformation of an existing rock by heat, pressure or chemically active fluids, or combinations of these three processes.


Volcanic rocks which have been metamorphosed by heat and / or pressure within the Earth.


Metamorphic rocks derived from sedimentary rocks.


  1. The study of minerals.
  2. The mineral composition of rocks and ores

Mineral Resource

An estimated tonnage and grade of mineralisation in the ground determined as prescribed by the JORC Code

Model block

A finite 3D element of the Earth for which the average grade can be estimated from drill data


A very soft group of minerals that typically form microscopic crystals, forming a clay.


Million Tonnes

Mwashia or Mwashya

A member of the Katangan Supergroup, dated to around 760 million years.


Geological age from 23 million years to present (0.5 million years).


A geological era lasting from 1000 to 542 million years ago. During the Neoproterozoic there occurred the most severe worldwide glaciations in the Earth’s history, believed to have been so extreme as to bring icecaps to the equator, leading to a state known as the “Snowball Earth”.


The chemical symbol for nickel.

NI 43-101

Canadian National Instrument 43-101, “Standards of Disclosure for Mineral Projects”.


An area of younger rocks surrounded by older rocks.


A mineral or an aggregate of minerals from which a valuable constituent, especially a metal, can be profitably mined or extracted.

Ore Reserve

That part of a Mineral Resource which can be demonstrated to be worked profitably when all modifying factors are taken into account.

Pan African Orogeny

A major period of mountain building approximately 900 million years ago.

Pan African Thermal Event

A widespread thermo-tectonic event dated around 550 million years ago, seen in rocks from the Arabian peninsula, Africa, Madagascar, southern India, Sri Lanka and east Antarctica.


The chemical symbol for lead.

Percussion drilling

See RAB and RC


A very course grained igneous rock having a grain size of 3cm or larger.


Platinum Group Elements or Platinum Group Metals. Six metals (ruthenium, rhodium, palladium, osmium, iridium, and platinum), which have similar physical and chemical properties, and tend to occur together in the same mineral deposits.


Parts per billion by weight (ie milligrams per tonne)


Parts per million by weight (ie grams per tonne)


Use of the cheaper and faster reverse circulation method to drill the upper parts of deep holes, before switching to diamond drilling to intersect an anticipated mineralised zone. The pre-collar part of a drill hole is usually expected to be barren of significant mineralisation.


A geological Eon lasting from 2390 to 570 million years ago.

Quantitative Phase Analysis (QPA)

A powerful method for determining the quantities of crystalline and amorphous components in multiphase mixtures.


Rotary air blast. Percussion drilling using a pneumatic hammer, cutting the rock into chips which are flushed to the surface through the space between the drill pipe and the wall of the hole.


Reverse circulation. Percussion drilling using an air-cooled bit, cutting the rock into chips which are flushed to the surface through a double walled pipe by the air pressure.


The percentage of a metal which can be successfully extracted from its ore by a particular chemical or physical process or a combination of processes.


Old miners’ name for a gold-bearing zone, usually a gold-bearing quartz vein.


The mantle of material which lies between fresh bedrock and the air or water at the Earth’s surface, including weathered products of the underlying bedrock and/or materials transported by wind, water or gravity.


The lowermost component of the Katangan Supergroup, deposited between 880 and 750 million years ago. Most of the copper deposits of the Zambian copperbelt occur within the Roan.


South African Code for Reporting of Exploration Results, Mineral Resources and Mineral Reserves.


A sedimentary rock which has partical sizes from 0.06mm to 2mm.


A clay mineral consisting of hydrated magnesium aluminium silicate and occurring in metamorphic rocks such as serpentine.

Sedimentary rocks

Rocks formed by the consolidation of sediments, which may include clastic fragments derived from parent rocks by weathering or erosion by water, ice or wind; biogenic material such as shells; or chemical precipitates such as salt.

scanning electron microscope (SEM)

A type of electron microscope that images the surface of samples by scanning with a high-energy beam of electrons in a raster scan pattern. The electrons interact with the atoms that make up the sample producing signals that contain information about the sample’s surface morphology and composition.


Any of a group of greenish, brownish, or yellowish hydrated iron/manganese silicate minerals derived by alteration of igneous or metamorphic ultramafic rocks.


An ultrabasic rock that has been hydrothermally altered.

Shear zone

A linear zone of fracturing and tearing of the rocks which can provide passage for hydrothermal mineralising fluids


A coarse-grained metamorphic rock produced by contact metamorphism of carbonate rocks, usually formed by chemical metasomatism near a contact between the carbonates and magmatic intrusions such as granites. Metal-rich metasomatic replacement mineralisation in the skarn setting is known as a skarn deposit.


Any of a group of clay minerals of which montmorillonite and saponite are members


The study of stratified sedimentary and volcanic rocks, especially their character and sequence in time, and the correlation between beds in different localities.


A U-shaped fold with the youngest rocks in the centre.


A white, grey, brown, or pale green mineral, found in metamorphic rocks. It is used in the manufacture of talcum powder and electrical insulators.

Tank leaching

A process to extract metals from mined ore, which is crushed and ground to powder, then placed with a leaching agent in large tanks where they are agitated and sometimes heated together. The metals dissolve in the leaching agent to produce a “pregnant solution” which is drawn off and processed to precipitate them out. The residual slurry is pumped out to tailings disposal. (Also called vat leaching).


A metric tonne of 1000 kilograms, abbreviation t


The chemical symbol for uranium.


A phase of mountain building whose precise dates are uncertain but which probably occurred about 1800–1700 Ma ago, producing what is now a NW trending belt in southern Tanzania, northern Zambia, and the eastern Congo.


Igneous rocks with very low silica and potassium content but high in iron and magnesium, usually composed of greater than 90% mafic minerals (dark coloured minerals with high magnesium and iron content).

Volcanic rocks

Rocks produced by or associated with volcanic eruptions, including lava and ash.


A geological sequence which includes both volcanic and sedimentary rocks.

Whittle optimisation

A design process for open pit mines which aims to maximise the profitability of the operation while satisfying operational constraints such as the safety of pit walls and a practical mining schedule.

X-ray diffraction (XRD)

An analytical technique providing information about the crystallographic structure, chemical composition, and physical properties of materials by observing the diffraction or scattering pattern produced by a beam of X-rays hitting the sample.


The chemical symbol for zinc.

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