Home > Glossary of terms

Alluvial:

the product of sedimentary processes in rivers, resulting in the deposition of alluvium (soil deposited by a river).

Auriferous:

a substance that contains gold.

Beneficiation:

the process of adding value to gold products by transforming gold bullion into fabricated gold products.

Brownfields project:

a potential mining site with known mineral resources.

Call option:

a contract that permits the owner to purchase an asset at a specified price on or before a specified date.

Capital expenditure:

the expenditure on mining assets to both maintain and expand operations.

Cash cost:

a measure of the average cost of producing an ounce of gold, calculated by dividing the total cash working costs in a period by the total gold production over the same period. Working costs represent total operating costs less certain administrative expenses, royalties and depreciation. In determining the cash cost of different elements of the operations, production overheads are allocated pro rata.

Channel width:

the total thickness of the entire reef unit to be mined, including internal waste, but excluding external waste.

Contained ounces:

gold ounces from which neither extraction, dilution nor processing recovery losses have been deducted.

Cut-off grade:

the grade at which the total profit from mining the orebodies, under a specified set of mining parameters, is maximised.

Depletion:

the decrease in quantity of ore in a deposit or property resulting from extraction or production.

Development:

activities (including shaft sinking and on-reef and off-reef tunnelling) required to prepare for mining and maintain a planned production level and those costs to enable the conversion of mineralised material to reserves.

Exploration:

activities associated with ascertaining the existence, location, extent or quality of mineralised material, including economic and technical evaluations of mineralised material.

Faulting:

the process of fracturing that produces a displacement of rock.

Footwall:

the underlying side of a fault, orebody or stope.

Forward contract:

an agreement for the sale and purchase of an asset at a specified future date at a fixed price.

Forward currency sale contract:

an agreement for the sale of a specific quantity of one currency for another currency at a specified future date at a fixed exchange rate.

Forward purchase:

an agreement for the purchase of a commodity at a specified future date at a fixed price.

Forward sale:

the sale of a commodity for delivery at a specified future date and price.

Gold assets:

the after-tax net asset value of the company’s gold assets including gold exploration properties and hedging gains or leases.

Gold reserves:

the gold contained within proven and probable reserves on the basis of recoverable material (reported as mill delivered tonnes and head grade).

Grade:

the average amount contained in a tonne of gold, leaving ore expressed in grams per tonne of ore.

Greenfield:

a potential mining site of unknown quality.

Hangingwall:

the overlying side of a fault, orebody or stope.

Head grade:

the grade of the ore as delivered to the metallurgical plant.

In situ:

in place, i.e. within unbroken rock or still in the ground.

Life-of-mine:

the number of years that an operation is planning to mine and treat ore, taken from the current mine plan.

IRR:

internal rate of return, the investment appraisal that takes the time value of money fully into account.

Level:

the workings or tunnels of an underground mine that are on the same horizontal plane.

Marked-to-market:

the current fair value of a derivative based on current market prices or to calculate the current fair value of a derivative based on current market prices, as the case may be.

Measures:

conversion factors from metric units to U.S. units are provided below.

Metallurgical plant:

a processing plant used to treat ore and extract the contained gold.

Metallurgy:

in the context of mining, the science of extracting metals from ores and preparing them for sale.

Mill delivered tonnes:

a quantity, expressed in tons, of ore delivered to the metallurgical plant.

Milling/mill:

the comminution of the ore, although the term has come to cover the broad range of machinery inside the treatment plant where the gold is separated from the ore.

Mineable:

that portion of a mineralised deposit for which extraction is technically and economically feasible.

Metric units – US equivalent

1 tonne = 1 t = 1.10231 short tons

1 gram = 1 g = 0.03215 ounces

1 gram per tonne = 1 g/t = 0.02917 ounces per short ton

1 ounce = 31.15 grams

1 kilogram per tonne = 1 kg/t = 29.16642 ounces per short ton

1 kilometre = 1 km = 0.621371 miles

1 metre = 1 m = 3.28084 feet

1 centimetre = 1 cm = 0.3937 inches

1 millimetre = 1 mm = 0.03937 inches

1 hectare = 1 ha = 2.47105 acres

Mineral resource:

A mineral resource is a concentration or occurrence of material of economic interest in or on the earth’s crust in such form, quality and quantity that there are reasonable and realistic prospects for eventual economic extraction. The location, quantity, grade, continuity and other geological characteristics of a mineral resource are known, estimated from specific geological evidence and knowledge, or interpreted from a well-constrained and portrayed geological model. Mineral resources are subdivided, in order of increasing geological confidence, into inferred, indicated and measured categories. The mineral resources are inclusive of those resources which have been modified to produce ore reserves.

Mineralisation:

the presence of a target mineral in a mass of host rock.

Mineralised material:

a mineralised body that has been delineated by appropriately spaced drilling and/or underground sampling to support a sufficient tonnage and average grade of metals to warrant further exploration. Such a deposit does not qualify as a reserve until a comprehensive evaluation based upon unit cost, grade, recoveries, and other material factors conclude legal and economic feasibility.

NPV:

net present value.

Open-pit/Opencast/open cut:

mining in which the ore is extracted from a pit. The geometry of the pit may vary with the characteristics of the orebody.

Ore:

a mixture of mineralised material from which at least one of the contained minerals can be mined and processed at an economic profit.

Ore grade:

the average amount of gold contained in a tonne of gold bearing ore expressed in ounces per tonne.

Ore reserve:

that part of mineralised material which at the time of the reserve determination could be economically and legally extracted or produced. Ore reserves are reported as general indicators of the life of mineralised materials. Changes in reserves generally reflect: Grades of ore actually processed may be different from stated reserve grades because of geological variation in different areas mined, mining dilution, losses in processing and other factors. Recovery rates vary with the metallurgical characteristics and grade of ore processed. Neither reserves nor projections of future operations should be interpreted as assurances of the economic life of mineralised material nor of the profitability of future operations.

Orebody:

a well defined mass of mineralised material of sufficient mineral content to make extraction economically viable.

Ounce:

one Troy ounce, used in imperial statistics equals 31.1035 grams. A kilogram = 32.1507 ounces

Overburden tonnes:

tonnes that need to be removed to access an ore deposit.

Pay limit:

the breakeven grade at which the orebody can be mined without profit or loss, calculated using the forecast gold price, working costs and recovery factors.

Price to earnings ratio:

the current share price divided by adjusted earnings per share.

Probable reserves:

reserves for which quantity and grade and/or quality are computed from information similar to that used for proven reserves, but the sites for inspection, sampling, and measurement are farther apart or are otherwise less adequately spaced. The degree of assurance, although lower than that for proven reserves, is high enough to assume continuity between points of observation.

Prospect:

an area of land with insufficient data available on the mineralisation to determine if it is economically recoverable, but warranting further investigation.

Prospecting licence:

an area for which permission to explore has been granted.

Proven reserves:

reserves for which: (a) quantity is computed from dimensions revealed in outcrops, trenches, workings or drill holes; grade and/quality are computed from the results of detailed sampling; and (b) the sites for inspection, sampling and measurement are spaced so closely and the geologic character so well defined that size, shape, depth and mineral content of reserves are well established.

Put option:

a contract that enables the owner to sell an asset at a specified price on or before a specified date.

Put purchase:

a right, but not an obligation, of a party, purchased at a specified cost, to sell a specific quantity of a commodity at a specified future date at a fixed price.

Recovery grade:

the actual grade of ore realised after the mining and treatment process.

Reef:

a gold-bearing sedimentary horizon, normally a conglomerate band, that may contain economic levels of gold.

Refining:

the final stage of metal production in which impurities are removed from the molten metal by introducing air and fluxes. The impurities are removed as gases or slag.

Rehabilitation:

the process of restoring mined land to a condition approximating its original state.

Sampling:

taking small pieces of rock at intervals along exposed mineralisation for assay (to determine the mineral content).

Shaft:

a shaft provides principal access to the underground workings for transporting personnel, equipment, supplies, ore and waste. A shaft is also used for ventilation and as an auxiliary exit. It is equipped with a surface hoist system that lowers and raises conveyances for men, materials and ore in the shaft. A shaft generally has more than one conveyancing compartment.

Spot price:

the current price of a metal for immediate delivery.

Stope:

the underground excavation within the orebody where the main gold production takes place.

Stripping:

the process of removing overburden to expose ore.

Tailings:

finely ground rock from which valuable minerals have been extracted by milling.

Tailing dam/Slimes dam:

dams or dumps created from tailings or slimes.

Tonnage:

quantities where the ton or tonne is an appropriate unit of measure. Typically used to measure reserves of goldbearing material in situ or quantities of ore and waste material mined, transported or milled.

Tonne:

one tonne is equal to 1 000 kilograms (also known as a metric ton).

Trenching:

making elongated open-air excavations for the purposes of mapping and sampling.

Trend:

the arrangement of a group of ore deposits or a geological feature or zone of similar grade occurring in a linear pattern.

Unconformity:

the structural relationship between two groups of rock that are not in normal succession.

Waste:

ore rock mined with an insufficient gold content to justify processing.

Waste rock:

the non-mineralised rock and/or rock that generally cannot be mined economically that is hoisted to the surface for disposal on the surface normally close to the shaft on an allocated dump.

Yield:

the actual grade of ore realised after the mining and treatment process.

Glossary of geological terms

Below infrastructure:

That part of a company’s ore reserve that can only be accessed following certain capital expenditure which has yet to be approved.

Craton:

A part of the earth’s crust that has attained stability and has been little deformed for a long period of geological time.

Diorite:

A group of plutonic rocks intermediate in composition between acidic and basic.

Felsic:

An igneous rock having abundant light coloured minerals.

Graben:

A block of rock that lies between two faults, and has moved downward to form a depression between two adjacent fault blocks.

Greenstone:

A field term for any compact dark green altered or metamorphosed basic igneous rock that owes its colour to chlorite.

Horst:

A block of rock that lies between two faults and has moved upward relative to the two adjacent fault blocks.

Kaapvaal Craton:

The ancient protocontinental basement of South Africa.

Lacustrine:

Pertaining to sediments formed in lakes.

Mafic:

An igneous rock composed chiefly of dark, ferromagnesium minerals.

Ophiolite:

A group of mafic and ultramafic igneous rocks derived by metamorphism, whose origin is associated with an early phase of the development of a geosyncline.

Plunge:

The inclination of a fold axis or other linear feature, measured in the vertical plane.

Sub-outcrop:

A rock stratum that unconformably underlies another rock stratum.

Syncline:

Concave fold in stratified rock, in which strata dip down to meet in a trough.

Witwatersrand Basin:

A sedimentary basin in South Africa.