Glossary

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A
Alluvial
Relating to deposits made by flowing water, washed away from one place and deposited in another.
Assay
An analysis to determine the presence, absence or concentration of one or more chemical components.
B
Ball Mill
A large steel cylinder containing steel balls into which crushed ore is fed.  The ball mill is then rotated, causing the balls to cascade and grind the ore.
Belt
An area characterized by a particular assemblage of mineral deposits, or by one or more characteristic types of mineralization.
Bench
A ledge that, in open pit mines and quarries, forms a single level of operation above which minerals or waste materials are excavated from a contiguous bank or bench face.  The mineral or waste is removed in successive layers, each of which is a bench.
Bio-Oxidation
Bio-oxidation is a pre-treatment process, which oxidizes and removes sulphides that have encapsulated gold. The exposed gold is then leached using traditional methods, such as cyanide. This pre-treatment has improved gold recovery and has allows the development of previously uneconomical zones.
Blast Hole
A hole drilled for the purpose of inserting an explosive charge in a material to be blasted.
Block Model
A model that utilizes a three-dimensional block grid of a fixed or variable size to estimate in-situ resources and reserves.
Breccia
Rock consisting of fragments, more or less angular, in a matrix of finer-grained or cementing material.
C
Capping
Individual assays above this assay grade value are limited to prior grade interpolation.  Also referred to as high-grade top cutting.
Carbon-In-Leach (CIL)
A recovery process in which a slurry of gold ore, carbon granules and cyanide are mixed together.  The cyanide dissolves the gold, which is then absorbed by the carbon.  The carbon is subsequently separated from the slurry and the gold removed from the carbon.
Circuits
Facilities for removing valuable minerals from ore so that it can be processed and sold.
Closure Plan
A plan designed to ensure public safety and restore the physical, chemical and biological quality of the area disturbed by mining to an acceptable level. It must aim at leaving the area in such a way that the rehabilitated property does not become a burden to society after the mining operation is over.
Colluvium
A loose deposit of rock debris accumulated through the action of gravity at the base of a cliff or slope.
Concentrate
A product containing valuable metal from which most of the waste material in the ore has been eliminated.
Concession
Grants made under a system whereby the state or the private owner has the right to grant concessions or leases to mine operators subject to certain general restrictions.  Concession systems are used in almost every mining country in the world except the United States.
Corporate Responsibility
A form of corporate self-regulation integrated into a business model where companies embrace the responsibility for the impact of their activities on the environment, consumers, employees, communities and stakeholders.
Cut-off grade
The minimum metal grade at which a tonne of rock can be economically mined and processed.
Cuttings
The particles of rock produced in a borehole by the abrasive or percussive action of a drill bit.
Cyanidation
A method of extracting gold or silver by dissolving it in a weak solution of sodium cyanide.
Cyanide
A chemical compound containing carbon and nitrogen used to dissolve gold from ore.
Cyclone
A cone-shaped separator into which pulp is fed and then spun in a circular path.  Coarser and heavier solids exit at the apex of the cone (cyclone underflow) while finer particles overflow from the central vortex (cyclone overflow).
D
Deposit
A mineralized body that has been physically delineated by sufficient drilling, trenching and/or underground work and found to contain a sufficient average grade of metal or metals to warrant further exploration and/or development expenditures; such a deposit does not qualify as a commercially mineable orebody or as containing mineral reserves until final legal, technical and economic factors have been resolved.
Depressurization
The mechanical process of lowering or removing hydraulic water pressure from a geological structure or unit without the complete removal of the contained water.
Dewatering
The mechanical process of removing or controlling water contained within a geological structure, unit or excavated opening such as an open pit or underground working.
Diamond Drill
A type of rotary drill that cuts by abrasion rather than percussion.  The cutting bit is set with diamonds and is attached to the end of long hollow rods through which water is pumped to the cutting face.  The drill cuts a core of rock which is recovered in long cylindrical sections, approximately two centimetres or more in diameter.
Dilution
The effect of waste or low-grade ore being included in mined ore, increasing tonnage mined and lowering the overall ore grade.
Dip
The angle at which a bed, stratum or vein is inclined from the horizontal, measured perpendicular to the strike and in the vertical plane.
Doré
Unrefined gold and silver bullion bars usually consisting of approximately 90 % precious metals that will be further refined to almost pure metal. 
Drill Core
A long cylindrical sample of rock, approximately two centimetres in diameter, brought to the surface by diamond drilling.
E
Electrowinning
Recovery of a metal from ore by means of electro-chemical processes.
Environmental Assessment
The process of identifying, predicting, evaluating and mitigating the biophysical, social and other relevant effects of development proposals prior to making major decisions and commitments.
Environmental Management System (Ems)
A framework developed by an organization to help improve its environmental performance by taking environmental considerations into account when making decisions and managing risks. 
F
Facies
A term of wide application, referring to such aspects of rock units as rock type, mode of origin, composition, fossil content or environment of deposition.
Fault
A fracture in the earth’s crust, along which there has been displacement of the two sides relative to one another and parallel to the fracture.  The displacement may be a few inches or many miles long.
Feasability Study
A comprehensive study of a deposit in which all geological, engineering, operating, economic and other relevant factors are considered in sufficient detail that it could reasonably serve as the basis for a final decision by a financial institution to finance the development of the deposit for mineral production.
Fire Assay
The assaying of metallic ores, in particular gold and silver, at high temperatures with an assay furnace.
Flotation
A milling process by which some mineral particles are induced to become attached to bubbles of froth and float.  Others are left to sink so that the valuable minerals are concentrated and separated from the remaining rock or mineral material.
Flowsheet
A diagram showing the progress of material through a preparation or treatment plant. It shows the crushing, screening, cleaning or refining processes to which the material is subjected from the run-of-mine state to the clean and sized products. The size range at the various stages may also be shown.
Fresh
Rock surface that has not been subjected to or altered by surface weathering, such as a rock newly exposed by fracturing.
G
G/T
Grams per tonne.
Geotechnical Drilling
Drilling for the purpose of collecting information to be used in rock stability analyses.
Grade
The amount of mineral in each tonne of ore.
Gravimetric
Of or relating to measurement by weight.
Gravity Concentration
The separation of grains of minerals using a concentration method based on the different densities of those minerals.
H
Heap Leach
A process used for the recovery of gold from ore (usually low-grade ore) whereby crushed ore is laid on a slightly sloping, impervious pad and uniformly leached by the percolation of a cyanide solution trickling through the ore by gravity to a pond or other collection system.
Host Rock
The body of rock in which mineralization of economic interest occurs.
Hydrothermal Alteration
Alteration of rocks or minerals by the reaction of hydrothermal water with pre-existing solid phases.
I
ISA Mill
A high intensity, stirred mill used in the fine grinding of mineral ores.  It was developed by Mount Isa Mines in the 1990s.
Igneous
A rock or mineral that has solidified from molten or partly molten material, i.e., from a magma.  Also applied to processes leading to, related to or resulting from the formation of such rocks.
In-Fill Drilling
Drilling within a defined mineralized area to improve the definition of the known mineralization.
Indicated mineral resource
An indicated mineral resource is that part of a mineral resource for which quantity, grade or quality, density, shape, and physical characteristics can be estimated with a level of confidence sufficient to allow the appropriate application of technical and economic parameters, to support mine planning and evaluation of the economic viability of the deposit. The estimate is based on detailed and reliable exploration and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes that are spaced closely enough for geological and grade continuity to be reasonably assumed.
Induced Polarization (IP) Survey
An electrical geophysical survey method used to aid in geological mapping and the identification of potential mineralized zones containing sulphide minerals.
Inferred mineral resource
An inferred mineral resource is that part of a mineral resource for which quantity and grade or quality can be estimated on the basis of geological evidence and limited sampling and reasonably assumed but not verified, geological and grade continuity. The estimate is based on limited information and sampling gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes.
Intrusive
Rock which, while molten, penetrated into or between other rocks but solidified before reaching the surface.
J
Joint Venture (JV)
The partnership of two or more companies in a specific operation, each agreeing to share profit or loss according to ownership percentage. Operational control often depends on ownership percentage.
K
Kaolinization
The formation of the mineral kaolin as a result of weathering or hydrothermal alteration.
Kriging
A commonly used method to compute resources using a weighted moving average to interpolate values (grades) from a sample data set onto a grid.
M
Matrix
The non-valuable minerals in an ore.
Measured Mineral Resource
A measured mineral resource is that part of a mineral resource for which quantity, grade or quality, density, shape and physical characteristics are so well established that they can be estimated with confidence sufficient to allow the appropriate application of technical and economic parameters, to support production planning and evaluation of the economic viability of the deposit. The estimate is based on detailed and reliable exploration, sampling and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes that are spaced closely enough to confirm both geological and grade continuity.
Micron
Former term for “micrometer,” meaning a unit of length equal to one-millionth of a metre.
Mill
A processing facility where ore is finely ground and thereafter undergoes physical or chemical treatment to extract the valuable metals.
Mineral Reserves
The economically mineable part of a measured or indicated mineral resource demonstrated by at least a preliminary feasibility study.  This study must include adequate information on mining, processing, metallurgical, economic and other relevant factors that demonstrate, at the time of reporting, that economic extraction can be justified.  A mineral reserve includes diluting materials and allowances for losses that may occur when the material is mined.

Proven mineral reserve:The economically mineable part of a measured mineral resource demonstrated by at least a preliminary feasibility study.  This study must include adequate information on mining, processing, metallurgical economic and other relevant factors that demonstrate, at the time of reporting, that economic extraction is justified.

Probable mineral reserve:The economically mineable part of an indicated mineral resource, and in some circumstances a measured mineral resource, demonstrated by at least a preliminary feasibility study.  This study must include adequate information on mining, processing, metallurgical, economic and other relevant factors that demonstrate, at the time of reporting, that economic extraction can be justified.
Mineral Resources
A concentration or occurrence of diamonds, natural solid inorganic material, or natural solid fossilized organic material including base and precious metals, coal, and industrial minerals in or on the earth’s crust in such form and quantity and of such a grade or quality that it has reasonable prospects for economic extraction.  The location, quantity, grade, geological characteristics and continuity of a mineral resource are known, estimated or interpreted from specific geological evidence and knowledge.

Measured mineral resources:That part of a mineral resource for which quantity, grade or quality, densities, shape and physical characteristics are so well established that they can be estimated with confidence sufficient to allow the appropriate application of technical and economic parameters to support production planning and evaluation of the economic viability of the deposit.  The estimate is based on detailed and reliable exploration, sampling and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes that are spaced closely enough to confirm both geological and grade continuity.

Indicated mineral resources:That part of a mineral resource for which quantity, grade or quality, densities, shape and physical characteristics can be estimated with a level of confidence sufficient to allow the appropriate application of technical and economic parameters to support mine planning and evaluation of the economic viability of the deposit.  The estimate is based on detailed and reliable exploration and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes that are spaced closely enough for geological and grade continuity to be reasonably assumed.

Inferred mineral resources:That part of a mineral resource for which quantity and grade or quality can be estimated on the basis of geological evidence and limited sampling and reasonably assumed, but not verified, geological and grade continuity.  The estimate is based on limited information and sampling gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes.
Mineralization
The concentration of minerals within a body of rock.
N
Net Smelter Return (NSR) Royalty
A royalty payment made by a producer of metals, normally to a previous property owner, based on gross mineral production from the property, less deduction of certain costs.
Non-Governmental Organization (NGO)
A not-for-profit group largely funded by private contributions and operating outside of institutionalized government or political structures. NGOs focus on environmental, social and economic issues at local, regional, national and international levels.
Nugget Effect
Grade variation due to measurement errors and short-range special variation at short distances.
O
Open Pit
A mine that is entirely open to the surface.
Ore
A metal or mineral, or a combination of these, of sufficient quality and quantity to enable it to be mined at a profit.
Ounce (Oz)
Troy ounces = 31.103 grams.
Oxidation
A chemical reaction caused by exposure to oxygen that results in a change in the chemical composition of a mineral.
P
Pit Design
An open pit contour surface based on an optimized pit shell that has been engineered in detail by adding access ramps and by smoothing of the pit walls.  Pit designs are supported by detailed mining plans.
Pit Shell
A non-engineered open pit contour surface produced by optimization software at a particular gold price, without consideration to equipment access and mining plans.
Placer
A deposit of sand or gravel that contains particles of gold or other heavy, valuable minerals.  The common types are stream gravels and beach sands.
Preg-Robbing
When leaching ore, a dilute cyanide solution is used to dissolve the gold to produce a “pregnant solution”.  When carbon mineralization is present in the ore it may re-absorb some of the gold from the pregnant solution.  This process is referred to as “preg-robbing”.
Pulp
A mixture of ground ore and water capable of flowing through suitably graded channels as a fluid.
Pyrite
An iron sulfide mineral, normally of little value and sometimes referred to as “fool’s gold”.
R
Reclamation
The process by which lands disturbed as a result of mining activity are reclaimed back to a beneficial land use. Reclamation activity includes the removal of buildings, equipment, machinery and other physical remnants of mining, closure of tailings impoundments, leach pads and other mine features and contouring, covering and re-vegetation of waste rock piles and other disturbed areas.
Recovery
The proportion of valuable material obtained as a result of processing an ore.  It is generally stated as a percentage of valuable metal in the ore that is recovered compared to the total valuable metal present in the ore.
Refractory Material
Ore from which it is difficult to recover valuable substances.  Refractory material must be pre-treated before gold can be recovered from it through conventional cyanidation.
Reserves
Means mineral reserves.
Resources
Means mineral resources.
Responsible Mining
A comprehensive and transparent minerals activity that respects the rights of all stakeholders, especially those of local people, operates safely, protects the environment, minimizes the impact on human health, embraces the best international practices and upholds the rule of law while generating benefits for host countries.
Reverse Circulation (RC)
The circulation of bit-coolant and cuttings-removal liquids, drilling fluid, mud, air or gas down a borehole outside the drill rods and upward inside the drill rods.  Also called “countercurrent” or “counterflush”.
Roasting
A method of oxidizing refractory ore using very high temperatures to thermally decompose the sulphide minerals encapsulating the gold, which is ultimately recovered using conventional cyanide leaching.
S
Schist
A strongly foliated crystalline rock that can be readily split into thin flakes or slabs due to the well developed parallelism of more than 50% of the minerals present in it.
Sedimentary Rocks
Secondary rocks, such as lime, shale and sandstone, formed from material derived from other rocks.
Semi-Autogenous (SAG) Grinding
A method of grinding rock into fine sand, in which the grinding media consist of larger chunks of rock and steel balls.
Shear Key
The removal of weak materials in a specified area and replacement with engineered fills to provide improved shear resistance and impermeability in the foundation of a dam.
Shearing
Deformation resulting from stresses that cause, or tend to cause, contiguous parts of a body to slide relative to each other.
Sinistral
A fault on which the displacement is such that the side opposite the observer appears displaced to the left.
Slurry
A suspension of fine solid particles in a liquid, not thick enough to consolidate as a sludge.
Stockwork
A mineral deposit consisting of a three-dimensional network of planar to irregular veinlets closely enough spaced that the whole mass can be mined.
Strike
The horizontal direction or trend of a geologic structure.
Strike-Slip Fault
A fault on which the movement is parallel to the fault’s strike.
Strip (Or Stripping) Ratio
The tonnage or volume of waste material that must be removed to allow the mining of one tonne of ore in an open pit.
Sustainable Development
Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Centerra develops mineral deposits in a manner that does not restrict communities’ efforts to sustain themselves and strives to catalyze economic activity that promotes long-term sustainability among our communities and their surroundings.
T
Tailings
The material that remains after recoverable metals or minerals of economic interest have been removed from ore through milling.
Tailings Dam
A natural or man-made confined area suitable for depositing tailings.
Tellurides
Ores of the precious metals (chiefly gold) containing tellurium, a semi-metallic, trigonal mineral.
Thrust
An overriding movement of one crustal unit over another.
Ton
A ton or short ton is a British imperial measure of weight equivalent to 2,000 pounds.
Tonne
A tonne or metric tonne is about 10% greater in weight than a short ton and equivalent in weight to 1000 kilograms or 2,205 pounds.
V
Vein
A sheet-like body of minerals formed by fracture filling or replacement of host rock.
W
Waste
Barren rock in a mine, or mineralized material that is too low in grade to be mined and milled at a profit.
Z
Zero Discharge Site
No release of harmful or toxic material to the environment.