Glossary

A B C D E F G H I J K L M N O P Q R S T U V W XYZ
Abbreviations
Units of Concentration

Aerial photography
The taking of, or photos, acquired from aircraft used for surveying or other purposes.

AeromagneticSurvey
A survey made from the air for the purpose of recording magnetic characteristics of rocks.

Alluvial
Transported and deposited by water.

Anomaly
Value higher or lower than the expected or norm.

Anomalous
Outlining a zone of potential exploration interest but not necessarily of commercial significance.

Anticline
Upward arching fold or rock strata (antonym = syncline).

Archaean
The oldest rocks of the Precambrian Era, prior to 2500 million years.

Basalt
A fine-grained volcanic rock composed primarily of plagioclase feldspar and mafic minerals.

Basement
Usually synonymous with Archaean and Proterozoic terrain.

Base metal
Generally a metal inferior in value to the precious metals, eg. copper, lead, zinc, nickel.

Basic rocksvolcanics
Igneous rocks containing between 45 and 52% silica, distinct from acid or intermediate rocks.

Basin
A low area of the earth's crust in which sediments accumulate.

Bed
Individual sedimentary layer

Bedding
A rock surface parallel to the surface of deposition.

Bedrock
Any solid rock underlying unconsolidated material.

Breccia
Rock consisting of angular fragments in a finer grained matrix, distinct from conglomerate.

Bronzite
A mineral consisting of a iron-rich variety of enstatite.

Cambrian
A time period from 600 to 510 million years ago.

Carat
The unit of weight for diamonds (1 carat = 0.2 gram).

Chromite
An oxide of iron and chromium; an indicator mineral for kimberlite.

Clast
An individual constituent of sediment or sedimentary rock produced by the physical disintegration of a larger mass.

Clastic
A sedimentary rock composed of broken fragments of pre-existing rocks.

Complex
An assemblage of rocks or minerals intricately mixed or folded together.

Conglomerate
Sedimentary rock formed by the cementing together of rounded water- worn pebbles, distinct from breccia.

Country-rock
A general term applied to rock surrounding or penetrated by mineral veins.

Craton
A relatively immobile part of the earth, generally of large size.

Diamond
A cubic variety of crystalline carbon which may be of gem quality.

Diamondiferous
Containing diamond.

Diatreme
Breccia filled volcanic pipe formed by a gaseous explosion.

Dip
The angle at which a rock layer, fault of any other planar structure is inclined from the horizontal.

Dyke
A tabular intrusive body of igneous rock that cuts across bedding at a high angle.

EM Survey
Electro-magnetic survey to measure physical properties of the earth.

Enstatite
An orthorhombic mineral, 2[MgSiO 3 ] ; pyroxene group; a common rock-forming mineral in basalt, gabbro, norite, pyroxenite, and peridotite.

Fault
A fracture in rocks on which there has been movement on one of the sides relative to the other, parallel to the fracture.

Feldspar
A group of abundant rock-forming aluminous silicate minerals containing potassium, sodium, calcium or barium.

Float
Pieces of rock, separated from their parent strata, scattered over the surface.

Fault A fracture in rocks on which there has been movement on one of the sides relative to the other, parallel to the fracture.

Feldspar A group of abundant rock-forming aluminous silicate minerals containing potassium, sodium, calcium or barium.

Float Pieces of rock, separated from their parent strata, scattered over the surface.

Gabbro
A coarse-grained rock consisting of plagioclase and mafic minerals.

Geochemistry
Study of variation of chemical elements in rocks or soils.

Geochemical survey
The systematic study of the variation of chemical elements in rocks and soil.

Geomorphology
Study of the form and origin of natural land surfaces.

Geophysical survey
A systematic study of the variation of physical properties in rocks and soils.

Geophysics
Study of the earth by quantitative physical methods.

Graben
A large downthrown block bounded by faults.

Grab sample
Sample of rock or sediment taken more or less indiscriminately at any place.

Grade
Average quality of ore, metal or an element in a specified quantity of rock.

Grass-roots exploration
The initial phase of examining an area for the occurrence of mineralisation.

Hartzburgite
A variety of peridotite that consists essentially of olivine and enstatite or bronzite.

Ilmenite
Oxide of iron and titanium.

Intrusive
Having, while fluid, been injected into the earth's crust and solidifying before reaching the surface.

Kim berlite (-ic)
Volatile-rich, potassic, ultrabasic igneous rock which occurs as small volcanic pipes, dykes and sills, composed of olivine, phlogopite mica, calcite, pyroxene, apatite, spinel and indicator minerals. Often associated with diamond deposits.

Landsat
An unmanned satellite designed to provide multi-spectral imagery of the earth's surface.

Laterite
A red, residual soil, cemented in place, containing iron and aluminium oxides but leached of quartz.

Lava
Fluid rock such as that which issues from a volcano or a fissure in the earth's surface.

Lineament
A naturally occurring major linear feature in the earth's crust, often associated with mineral deposits.

Macrodiamond
A diamond larger than 0.4mm in diameter.

Mafic
A loosely used group-name for silicate minerals rich in iron and magnesium, and for rocks in which these minerals are abundant.

Magnetic Survey
Systematic collection of readings of the earth's magnetic field.

Magma
Naturally occurring mobile (generally fluid) rock material generated within the earth and capable of intrusion or extrusion.

Miocene
a division of geological time ranging between 23.8 million years and 5.3 million years ago.

Mica
A group of minerals consisting of phyllosilicates with sheet-like structures. (K, Na, Ca)(Mg, Fe, Li, Al) 2-3 (Al, Si)­­­­ 4 O 10 (OH, F) 2 .

Microdiamond
A diamond that is smaller than 0.4 mm in diameter.

Microprobe
of a mineral using an electron microprobe analyser.

Mineral Resource
A tonnage or volume of rock or mineralisation of economic interest.

Mineralisation
In economic geology, the introduction of valuable elements into a rock body.

Mobile Belt
A portion of the earth's crust that is more mobile, as shown by folds, faults etc, than the adjacent stable blocks.

Olivine
A rock forming silicate mineral series ranging from iron-rich to magnesium-rich. Important in mafic and ultramafic rocks.

Outcrop
The surface expression of a rock layer (verb: to crop out).

Palaeochannel
The remnants of a surface drainage system that was active in the geological past and may be buried now.

Palaeo
Relating to the past, ancient or fossil.

Permian
A division of geological time from 280 to 225 million years ago.

Peridotite
A general term for a coarse-grained plutonic rock composed chiefly of olivine with or without other mafic minerals such as pyroxenes.

Petrological studies
The systematic description of rocks in hand specimen and thin section.

PGE
Platinum group elements i.e. Platinum, Palladium, Rhodium, Osmium, Iridium, Rhuthenium.

Photogeology The geological interpretation of aerial photographs.

Picroilmenite
An oxide of iron and titanium; an indicator mineral for diamond exploration.

Pipe
A common term for a vertical cylindrical column-like mass of rock that cooled and solidified in the neck of a volcano.

Pyroclastic
A fragment of volcanic rock, resulting from explosive activity or eruption.

Pyrope garnet
The magnesium-aluminium end-member of the garnet group, characterised by a fiery-red colour. Associated with ultramafic rocks such as kimberlite.

Pyroxene
A group of chiefly magnesium-iron minerals.

RAB
Rotary Air Blast (as related to drilling)-A drilling technique in which the sample is returned to the surface outside the rod string by compressed air.

RC
Reverse Circulation (as relating to drilling)-A drilling technique in which the cuttings are recovered through the drill rods thus minimising sample losses and contamination.

Recent
Geological age from about 20,000 years ago to present (synonym: Holocene).

Reconnaissance
A general examination or survey of a region with reference to its main features, usually as a preliminary to a more detailed survey.

Remote Sensing Imagery
Geophysical data obtained by satellites processed and presented as photographic images in real or false colour combinations.

Resource
In-situ mineral occurrence from which valuable or useful minerals may be recovered, but from which only a broad knowledge of the geological character of the deposit is based on relatively few samples or measurements.

Sand
Unconsolidated sediment formed by fragments between 0.06 and 2.0mm in diameter.

Sandstone
A cemented or otherwise compacted detrital sediment composed predominantly of quartz grains.

Sediment
Rocks formed by the deposition of solids from water.

Shear (zone)
A zone in which shearing has occurred on a large scale so that the rock is crushed and brecciated.

Silica
Silicon dioxide, SiO 2 (cf . Quartz)

Silicified
Containing a high proportion of silicon dioxide.

Silt
A sediment in which most of the particles are between 0.0625mm and 0.0039mm diameter.

Soil sampling
Systematic collection of soil samples at a series of different locations in order to study the distribution of soil geochemical values.

Stockwork
An interlocking system of small veins or lodes.

Stratigraphy
The succession of superimposition of rock strata. Composition, sequence and correlation of stratified rock in the earth's crust.

Strike
The direction or bearing of the outcrop of an inclined bed or structure on a level surface.

Sulphide
A group of minerals in which one or more metals is found in combination with sulphur.

Surficial
Superficial. Characteristic of, pertaining to, formed on, situated at, or occurring on the earth's surface.

Syncline
A fold where the rock strata dip inwards towards the axis (antonym: anticline).

Tectonic
Relating to structural features.

Tertiary
A division of geological time ranging from 65 million years and 1.8 million years ago.

Triassic
A time period from approximately 248 to 212 million years.

Tuff (aceous)
A compacted pyroclastic rock of cemented volcanic ash.

Ultramafic rocks
Igneous rocks with very high magnesium and iron content containing less than 45% silicon dioxide.

Unconformable
Descriptive of rocks on either side of an unconformity.

Unconformity
Lack of parallelism between rock strata in sequential contact, caused by a time break in sedimentation.

Vein
A narrow intrusive mineral body.

Volcanic
Relating to the eruption of a volcano; Describes clastic fragments of volcanic origin.

Weathering
A process of change to rocks brought about by their exposure to oxygen and water.

Xenolith
A fragment of other rock or of an earlier solidified portion of the same mass enclosed in an igneous rock; an inclusion; an enclave.

Zircon
Zirconium silicate mineral.

ABBREVIATIONS

g gram

kg kilogram

km kilometre

km 2 square kilometre

m metre

m 2 square metre

m 3 cubic metre

Ma One million years ago

mm millimetre

t metric tonne =1,000kg

Ni Nickel

Cu Copper

Co Cobalt

Cr Chromium

UNITS OF CONCENTRATION

ppb parts per billion

ppm parts per million

md/100kg number of microdiamonds per 100kg

cpht Carats of diamond per 100 tonnes