A Glossary of Diamond Exploration and Mining Terms. Within explanations, any words highlighted blue have their own Glossary entry.

A - B - C - D - E - F - G - H - I - J - K - L - M - O - P - R - S - T - U - V - W - XYZ
	Aeolian	Sediment deposited by the action of wind.
	Airborne/ Aeromagnetic Magnetic survey	A survey conducted from the air for the purpose of recording the natural magnetic characteristics of rocks on and below the surface of the earth; kimberlites, the hostrock for diamonds, often have different magnetic characteristics and form a magnetic anomaly.
	Airborne Geophysics	Taking geophysical measurements (such as magnetometry) by airplane or helicopter.
	Alluvial	A sediment or gravel deposited by the action of stream or river in a river bed, flood plain, lake, fan at the foot of mountain slopes, or in estuaries that may or may not contain diamonds or precious minerals or both.
	Alteration	The recrystallisation of rock surrounding an igneous intrusion in response to the heat supplied by the intrusion.
	Amphibolite	A medium-grained dark coloured metamorphic rock composed of hornblonde and other minerals. Formed by medium grade metamorphism of basic igneous rocks.
	Anastomising	A value higher or lower then the expected which may outline a zone of potential exploration interest but not necessarily of commercial significance.
	Archaean craton	Old and stable parts of the earth crust, formed more than 2.5 billion years ago. They are good areas for finding diamond-bearing kimberlites.
	Archaean	The oldest rocks of the Precambrian era, formed over 2.5 billion years ago.
	Artisanal	Mining on a small scale, usually by hand and often without the assistance of machinery or mechanical tools. The term is sometimes extended to describe informal mining by a person or persons outside of a registered commercial organization.
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	Back filling	The process of refilling a void, created by mining, with waste rock or material resultant from successive mining operations.
	Basin	A depression in the earth’s crust filled with sediments. Laid down by rivers or at the bottom of a lake or sea.
	Bedrock	The competent rock type near surface overlain only by surficial material (soil, alluvial, etc.).
	Benefication	To increase the grade of ore after processing.
	Blow (or Enlargement)	A thickening (usually more than 10 m thick) of a dyke (usually about 1m thick).
	Bort / boart	Impure or discoloured diamond, unless as a gem. Used for industrial purposes.
	Breccia	Literally means ‘rubble’ and implies a rock deposited very to the source area. Also applied to angular volcanic rocks from a volcanic vent.
	Bulk sample	A very large sample usually taken from one site, and usually of several hundred tones weight.
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	Cainozoic/ Cenozoic	Era of geological time from 65 million years ago to date and includes the Tertiary and Quaternary Periods.
	Carat	A unit of weight for diamonds, equivalent to 0.2 of a gram.
	Channel	The deepest portion of stream through which the main volume or current of water flows.
	Chrome-diopside	A mineral (pyroxene) rich in crome and formed at great depth; common mineral in kimberlites.
	Clear diamond	A transparent diamond, free of inclusions and fractures.
	Concentrate sampling	The process of sampling for kimberlite indicator minerals.
	Contact	The surface along which two different rock types are in contact. Especially applicable where igneous rocks intrude country rocks.
	Core drilling	See Drillholes.
	Country Rock	The rock, or rocks, in which a mineral deposit is intruded or hosted.
	Craton	Area of the earth’s crust, which is no longer affected by mountain building processes and has been stable for the last 1,000 million years.
	Cretaceous	The geologic period dating from 144 million years ago to 65 million years ago. Noted for its deposition of chalks seen at the White Cliffs of Dover.
	Cut-off grade	Lowest grade of ore in a deposit that will recover mining costs; the cut-off grade determines the workable tonnage of an ore.
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	Deposit	Natural mass of coal, metal, or other material for mining in the earth.
	Diamond foundation	Diamonds are formed at great pressures (equivalent to depths of more than 150 km) and at temperatures of about 1,200 to 1,400 celsius; these conditions exist under Archaean cratons; diamonds have crystallized and exist underneath these Archaean cratons; often for billions of years; kimberlite volcanoes tap the diamonds from these depths and carry them to the surface of the volcanic explosion.
	Diamond / kimberlite Pipe	Nearly vertical, cylindrical body or opening in rock. Near surface the kimberlite pipes are found in clusters, at depth they coalesce and link up with dykes.
	Diamond	A crystallized variety of pure carbon, which may be of gem quality.
	Diamondiferous	Containing diamonds.
	Diatreme	The carrot shaped volcanic vent that has formed by explosive action and is characteristic of kimberlite pipes. Diatremes typically cut through non-volcanic basement rocks.
	Dip	The angle of inclination of a mineral deposit. The true dip is always measured in a vertical plane perpendicular to the strike.
	Discontinuity	Sudden interruption of a continuous phenomenon.
	DMS	Dense media separation; a process used to separate and concentrate the mineral being recovered from the other constituent minerals of the ore being mined.
	Dolerite	A dark coloured, medium grained igneous rock.
	Drill / drilled	The process of making/having made a hole, usually into the earth.
	Drillholes	A hole drilled into a rock or mineral deposit for the purpose of identifying its physical and chemical characteristics. Where a sample of the rock is to be recovered diamond impregnated drill bits are used and a core recovered.
	Duricrust	Deposit of the weathering zone, especially in subtropical environments, which may ultimately develop into a hardened mass.
	Dyke or Fissure	A wall-like body of igneous rock formed as the effect of having been pushed up into a crack in the material over it when in heated and liquid condition. Kimberlites move from great depths toward the surface along fissures; a few kilometers from the surface, the confining pressure of the overlying rocks is sufficient to contain the explosive gaseous kimberlite magma and a volcanic eruption results forming an explosive crater; a pipe or diatrema is formed, containing a chaotic mixture of kimberlite magma with shattered pieces of surrounding rocks (the kimberlite breccia) and with tuff layers on top formed by the falling back of ash into the volcano. Along the fissures underneath, the kimberlite cools and solidifies forming walls (dykes).
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	Eclogite	Very rare, course grained, igneous rock with a chemical composition similar to that of basalt but noted for the presence of the rare, bright green pyroxene omphacite, and red, almandine-pyrope garnets.
	Elluvial	sediment formed in place by the weathering of underlying rocks.
	En-echelon	The parallel or sub parallel alignment of separate structural features, which are arranged obliquely to a specific directional axis.
	Enlargement	See Blow.
	Exploitation	Mining of a natural resource deposit.
	Exploration	The search, using varied techniques, with the objective to discover and evaluate natural resource deposits of economic value.
	Exposure	Any geological feature that is visible, whether on surface or underground.
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	Fancy / fancies	Attractive, valuable and unusually rare colour of a gem.
	Fault	Approximately plane surface of fracture in a rock-body, caused by brittle failure, and along observable relative displacement has occurred between adjacent blocks.
	Fault zone	A region which is bounded by major faults within which subordinate faults may be found.
	Fissure	See Dyke.
	Flats	See Alluvial.
	Fluvial	Deposits in or pertaining to rivers.
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	Gem	Attractive minerals used as jewellery. A diamond free of flaws, as far as can be determined by a trained observer with the aid of a 10-power magnifying glass, and having a colour and other characteristics that do not deleteriously affect its value for use as a faceted ornamental diamond.
	Gem quality	Possessing the qualities of a gem.
	Geochemical survey	The sampling of rocks, stream sediments, and soils in order to locate abnormal concentrations of metallic elements or minerals. The samples are usually assayed by various methods to determine the qualities of elements or minerals in each sample.
	Geophysical survey	The exploration of an area in which physical properties relating to geology are used. Geophysical methods include seismic, magnetic, electromagnetic, gravity and induced polarization techniques.
	Geophysics	Science of the physical properties of the earth, its motion and forces and their effect.
	Gneisses	General petrological term applied to course-grained, banded rocks that formed during high-grade regional metamorphism.
	Grades	Internally, diamond grades for primary deposits are stated both in carats per tonne (ct / t) and carats per 100 tones (ct / 100t). In the case of alluvial deposits, industry practice is to quote grades in carats per tonne or carats per cubic metre.
	Granite	A light coloured, course-grained, igneous rock.
	Granulite	A course-grained, equigranular metamorphic rock, consisting of quartz, feldspar and the anhydrous ferromagnesium minerals pyroxene and garnet.
	Gravel	A course mixture of sand with pebbles and cobbles, laid down by rivers, with pebbles and cobbles derived from the erosion of rocks upstream in the catchment area of the river. Diamondiferous gravel contains diamonds derived from the erosion of other diamond-bearing rocks upstream.
	Grease table	A gently sloping table covered with grease which serves as a concentrator of diamonds.
	Groundmass	The finer grained materials of igneous rocks in which larger crystals and xenoliths are enclosed.
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	Hanging wall	The upper rock wall in a flat or inclined deposit (as opposed to footwall).
	HMS	Heavy Media Separation; a process used to separate and concentrate the mineral being recovered from the other constituent minerals of the ore being mined.
	Hydrology	The science of water, its properties and distribution, specifically of water under the earth.
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	Igneous rock	Applied to those rocks that have crystallized from a magma.
	Ilmenite	Natural ferrous titanite, a black, massive substance important as an ore of Titanium.
	Indicator minerals	Minerals formed together with diamonds at great depths and brought to the surface by the same kimberlites, indicator minerals are much more abundant than diamonds and are therefore much easier to trace in sample taken downstream in rivers draining knimberlite pipes or dykes; common indicator minerals are pyrope, ilmenite and chrome-diopside.
	Intersection	A specific feature intersected in a drillhole.
	Intrusion / intrusive	A volume of igneous (molten) rock which was injected into older rock.
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	Jig	Vibrating sleeve, moving up and down in water, concentrating the heavy minerals of a sand or gravel sample.
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	Karroo	A geographical area of Southern Africa, but also the name for a group of geological formations laid down in the late Paleozoic and Mesozoic age (about 300 to 100 million years ago).
	Kimberlite	An uneven grained, ultramafic, intrusive rock in which the visible minerals may include olivine, phlogopite, pyrope garnet, picroilmenite and chrome-diopside cemented by a groundmass, which may include serpentine, calcite and chromate. Kimberlite may be diamondiferous and, along with olivine lamproites, are the only know primary source of diamonds.
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	Lamproite	Another type of deep volcanic rock, that just as kimberlites, may bring diamonds from great depths to the surface.
	Laterite	Weathered product of rock, composed mainly of hydrated iron and aluminum oxides and hydroxides, and clay minerals. It is formed in humid tropical settings.
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	Macrodiamonds	Macrodiamonds are generally defined as diamonds larger than 0.5mm in size.
	Mafic	Applied to any igneous rock, which has a high proportion of pyroxene and olivine, such that it’s colour index is between 50 and 90 (i.e. dark).
	Magnetic anomaly	Zone where the magnitude and/or orientation of the earth’s magnetic field is notably higher or lower than adjacent areas.
	Magnetite	A magnetic iron oxide mineral.
	Metamorphism	The process of changing the characteristics of a rock in response to changes in temperature, pressure or volatile content.
	Microdiamonds	Current practice in Australia defines Microdiamonds as diamonds which will pass through a screen with 0.4mm in size.
	Mineable reserves	A natural aggregate of one or more minerals which, at a specified and place, may be mined and sold at a profit, or from which some part may be profitably separated.
	Materialization	A natural aggregate of one or more minerals.
	Mining Grade	The quality of a mineral ore after it has been mined and may reflect the effect of dilution from wall rock.
	Mining lease	Rights granted, usually by a government under specific legislation, to exploit a mineral subject to certain conditions.
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	Open cut mining	Mining in which large amounts of waste rock are excavated at surface in order to extract materials without sub-surface tinseling.
	Ore	A mineral or rock which can be worked economically.
	Ore body	Accumulation of minerals, distinct from the host rock, and rich enough in metal or commodity to be worth commercial exploitation.
	Ore grade	The concentration of an element of interest in a potentially mineable ore deposit.
	Outcrop	The part of a rock formation, which is exposed at the earth’s surface.
	Oxidation	The act or process of oxidizing.
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	Paleochannels	Old, ancient or past stream channels cut into the bedrock and which may be accompanied by remnant alluvial deposits.
	Pan	A rotary dish used to separate and concentrate the mineral being recovered from the other constituent minerals of the ore being mined.
	Parcel of Diamonds	A group of many diamonds, valued or sold as a group.
	Petrology	The study of rocks in general, including their occurrence, field relations, origins and history, and their mineralogy and textures.
	Phlogopite	A member of the mica group of minerals; occurs in metamorphosed limestones and less frequently in ultrabasic igneous rocks.
	Pitting	The digging of a pit, in exploration, sampling of alluvial sediments by shallow trial pits.
	Placer	A surficial mineral deposit formed by the mechanical concentration of mineral particles from weathered debris.
	Pluton	General term for a body of intrusive igneous rock irrespective of its shape, size or composition.
	Porphyritic	Of or like smaller grained igneous rocks with separate crystals of greater size.
	Positive gravity anomaly	Relatively elevated readings within a gravity survey which measures variations in the gravitational force across the earth’s surface.
	Precambrian	The geological time period extending from formation of the earth to 600 million years before the present.
	Processing plant	The chemical and, or, physical process required to recover and concentrate the mineral being mined into a sellable commodity.
	Prospective area	A possible area of valuable minerals for mining, oil producing etc.
	Proterozoic	Rocks formed between 2,500 and 600 million years ago.
	Pseudomorph	A secondary mineral, which has replaced an earlier mineral but retained its shape.
	Pyrope Garnet	Member of the garnet group of minerals, often mantle derived.
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	Radiometric dating	The most precise method of dating rocks in which the relative percentage of isotopes of a given radioactive element are estimated.
	Ramp	Inclined shaft.
	Recovery	The percentage of the situ commodity being mined for that is actually recovered after the beneficiation process.
	REE	Rare Earth Elements, including cerium and yttrium and others.
	Residual enrichment	The concentration of diamond in-situ by the removal by weathering processes of other constituent parts of its host rock.
	Resistivity	The electrical resistance per unit length of a unit cross-sectional area of a material, can be measured in geological materials.
	Rock mechanics	The study of the physical behavior of rocks and the mechanics of rock structures.
	Rutile	A natural form of titanium dioxide, a red-brown crystalline substance with a look of bright metal.
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	Sampling	To take a small amount of a substance as an example, for testing purposes etc.
	Schist	Any of a number of sorts of rocks having a structure of thin parallel plates or leaves and a tendency to become separated into them, formed from other rocks by heat and pressure acting on certain materials.
	Sediment	Matter deposited by water or wind.
	Serpentinised	The process whereby the high temperature primary ferromagnesian minerals in an igneous rock undergo alteration to a member of the serpentine group of minerals.
	Shear Zone	A region, narrow in comparison with its length, within which rocks have undergone intense deformation.
	Silcrete	Deposit of the weathering zone, especially in sub-tropical environments, which may ultimately develop into a hardened mass.
	Siltstone	A fine-grained sedimentary rock composed mainly of silt, intermediate in grain size between sandstone and shale, lacking the fissility of the latter.
	Statabound	Said of a mineral deposit confined to a single stratigraphic unit.
	Spectrometry	Measuring the natural radio-activity of rocks; This radio-activity is due to potassium, thorium and uranium, contained in the rocks; an airborne spectrometric survey measures the radio-activity due to potassium, thorium and uranium in the rocks and as a consequence gives some information about the composition of the rocks.
	Sortex machine	Mechanical device, which produced the final concentrate of diamonds and the associated heavy minerals by use of x-ray.
	Strike	The lineament of a geologic structure measure at 90 to its steepest altitude.
	Structurally-hosted	Said of mineral deposits that are contained in geologic structures like faults or folds.
	Sub-parallel / vertical	"Nearly" parallel, "nearly" vertical.
	Sulphide	Minerals consisting of a chemical combination of sulfur with a metal.
	Surface mining	Mining from surface of materials without sub-surface tinseling.
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	Tectonic	Deformation with the earth’s crust.
	Terrace (alluvial)	Sediments (sand with gravel) laid down by older (10,000 to million years ago) rivers and visible as flattened areas a few metres above the present river level.
	Tertiary	First sub-era of the Cenozoic Era, which began about 65 Ma ago and lasted approximately 63 Ma.
	TMI	Total Magnetic Intensity, refers to the total magnitude of the intensity of the earth’s magnetic field.
	Trenching	The process of locating the position of a dyke by digging trenches perpendicular to its expected strike.
	Tuff	The compacted (lithified) equivalent of a volcanic ash deposit.
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	Ultrabasic	An igneous rock that consists of ferromagnesian minerals and possesses no free quartz, and with less than 45% silica.
	Ultramafic	See Ultrabasic.
	UTM	Universal Transverse Mercator; a map grid reference system.
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	Volcanogenic	Formed by processes directly connected with volcanism.
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	Water table	The upper surface of ground water, or the level below which an unconfined aquifer is permanently saturated with water.
	Weathered	Having undergone the processes of chemical and physical change caused in rock exposed to the operation of air, rain, ice, snow, ground water, the sun’s rays, and so on.
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	Xenolith	An inclusion of a pre-existing rock in an igneous rock, often derived from the country rocks that have been intruded through.
	X-ray Diffraction Analysis	Laboratory technique used to identify minerals using X-rays.
	1VD	First vertical derivative refers to a particular processing of total magnetic intensity data to highlight certain features in the data.
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