| aeolian |
Sediments deposited by the action of wind. |
| aeromagnetic survey |
A magnetic survey conducted from an aircraft. |
| Ag |
Silver |
| alluvial |
Sediments deposited by the action of rivers or streams. |
| alteration |
The change in the mineral composition of a rock, commonly due to hydrothermal activity. |
| alteration zone |
A zone in which rock-forming minerals have been chemically changed. |
| amphibolite |
A metamorphic rock composed mainly of the mineral amphibole. |
| antiform, anticline |
Fold in the form of an arch. |
| Archaean |
The oldest geological era - Older than 2,400 million years. |
| arenite |
Sedimentary rock comprised of sand-sized material - Sandstone. |
| argentiferous |
Silver bearing. |
| argillite |
Fine-grained (clay, silt) sedimentary rock. |
| arkose |
A sandstone consisting of feldspar and quartz grains cemented by a mixture of quartz and clay minerals. |
| As |
Arsenic. |
| Au |
Gold. |
| auriferous |
Gold bearing. |
| AusIMM |
Australasian Institute of Mining and Metallurgy. |
| azimuth |
Compass direction. |
| basalt |
A dark, fine-grained extrusive igneous rock composed of feldspar and iron-magnesium rich minerals. |
| basement |
Older igneous and metamorphic rocks beneath usually unmetamorphosed sediments. |
| base-metal |
Copper, zinc, lead. |
| batholith |
Large mass of igneous intrusive rock. |
| BIF |
Banded Iron Formation. A rock consisting essentially of alternating bands of iron-oxides and cherty silica. |
| BLEG |
Bulk Leach Extractable Gold - a chemical analysis technique. |
| block, sub-block |
Mining tenement description: block = meridian block described as 1' latitude by 1' longitude, sub-block = part of a meridian block described as 30" latitude by 30" longitude. |
| boxwork |
The pattern of predominantly iron oxides left after the removal by weathering of sulphide minerals to form a gossan. |
| breccia |
Rock comprising angular fragments in a finer grained matrix. |
| Cainozoic |
The geological era from 65 million years to 2 million years before present. |
| calc-alkaline |
The name given to a suite of rocks comprising the volcanic association basalt-andesite-dacite-rhyolite or the plutonic association
gabbro-diorite-granodiorite-granite. Calc-alkaline rocks are typically developed on the continental side of plate subduction zones. |
| calcrete |
Superficial gravels cemented by secondary calcium carbonate. |
| calc-silicate |
A metamorphic rock usually formed as the result of metamorphism of impure limestone or dolomite sediments. |
| carbonaceous |
Rock containing significant quantities of carbon usually derived from organic material, often in the form of graphite. |
| carbonate |
Mineral, usually associated with limestone or dolomites (or their metamorphosed equivalents), containing CO3. |
| cassiterite |
Mineral. Ore of tin. |
| chalcedony |
Fine-grained quartz often formed as the weathering product of silicarich rock. |
| chalcopyrite |
Sulphide mineral. Ore of copper. |
| chert |
Fine grained quartz rock usually occurring as thin layers in sedimentary sequences. |
| chlorite |
A dark mineral of the mica family. |
| chrysocolla |
Mineral. Hydrated copper silicate usually occurring in the weathered zone of copper deposits. |
| chrysotile |
Mineral. A common variety of asbestos. |
| clastic |
Pertaining to sedimentary rocks composed of fragments eroded from pre-existing rocks. |
| Co |
Cobalt. |
| colluvium |
Unconsolidated overburden transported by gravity. |
| complex |
An assemblage of rocks of various ages and origins intricately mixed together. |
| conglomerate |
Sedimentary rock composed of rounded, coarse, pebble to boulder sized fragments of pre-existing rocks. |
| costean |
A trench excavated in the surface for the purpose of geological investigation. |
| Cr |
Chrome. |
| Craton |
A relatively large and stable block of the Earths crust. |
| Cretaceous |
The geological era from 135 million years to 65 million years before present. |
| crocidolite |
Mineral. A common variety of asbestos. |
| Cu |
Copper. |
| cupriferous |
Copper bearing. |
| cuprite |
Mineral. Oxide ore of copper. |
| cut-off grade |
The lowest or highest assay value that is included in a resource estimate. |
| dendritic |
Pertaining to branching drainage having the form of a tree. |
| detrital |
Particles or minerals derived from pre-existing rock by erosion. |
| diamond drilling |
Rotary drilling technique using diamond set or impregnated bits, to cut a solid, continuous core sample of the rock. The core sample is retrieved to the surface, in a core barrel, by a wireline. |
| dip |
The angle at which a rock stratum or planar structure is inclined from the horizontal. Also used in drilling for angle of drillhole from
horizontal. |
| dolerite |
A dark coloured medium grained igneous intrusive rock comprising the minerals pyroxene and feldspar. |
| dolomite |
A sedimentary rock composed of calcium and magnesium carbonates. |
| duricrust |
Layer of strongly cemented material in otherwise unconsolidated material at or near surface. |
| dyke |
A tabular body of intrusive igneous rock, crosscutting the host strata at a high angle. |
| EM survey |
Electromagnetic survey. A method of measuring the alternating magnetic fields associated with electrical currents artificially or
naturally maintained in the subsurface. |
| epithermal |
Descriptive of mineral deposits formed in rock fissures at shallow depths and low temperatures by ascending mineralizing solutions
fault A fracture in rocks on which there has been movement on one side relative to the other. |
| felsic |
Light coloured rocks containing an abundance of feldspars and quartz. |
| ferruginous |
Iron bearing. Usually pertains to iron-rich weathered rock. |
| fire assay |
Analytical technique involving heating a sample in a furnace to ensure complete extraction of all contained precious metal. |
| float |
Fragments of rock at surface that are loose and unattached to outcrop. |
| foreland basin |
A basin formed within a continental setting, often adjacent to a mountain range. |
| framboid |
Microscopic aggregate of pyrite grains in a roughly spherical form. |
| g |
gram. |
| g/t |
grams per tonne. |
| g/t Au, g/t Ag |
grams gold per tonne, grams silver per tonne. |
| Ga |
Billion years ago. |
| gabbro |
A dark coloured coarse grained igneous intrusive rock comprising the minerals pyroxene and feldspar. |
| geochemistry survey |
Systematic collection of data on the variation of chemical elements in rocks and soils. |
| geomorphology |
The description and interpretation of landforms. |
| geophysical survey |
Systematic collection of data on the variation of physical properties in rocks and soils. |
| glacial till |
A rock containing boulders in a clay matrix deposited from the action of ice in the form of glaciers. |
| gneiss |
A metamorphic rock with compositional banding of light and dark minerals, often granitic in composition. |
| gossan |
The oxidised 'cap' to underlying primary sulphides. |
| graben |
A downthrown block between two parallel faults. |
| granite |
Medium to coarse grained igneous intrusive rock comprised primarily of quartz and feldspar minerals. |
| granitoid |
A field term for coarse grained felsic igneous rocks resembling granite in composition. |
| graphite |
A soft, black mineral form of carbon, often found in metamorphic rocks derived from carbonaceous sediments. |
| gravity survey |
Systematic measurement and collection of the earth's gravitational field at the surface at regular intervals. Used to discern different rock types based on associated variations with differences in the distribution of densities, and hence rock types. |
| greenschist |
A schistose metamorphic rock which owes its green colour and schistosity to abundant chlorite and lesser epidote and/or actinolite. |
| greenschist facies |
A classification of the metamorphic grade of a rock, diagnostically defined by the metamorphic formation of chlorite and biotite at generally lower pressures and temperatures. |
| greenstone belt |
General term applied to elongate zones of volcanic and sedimentary rocks, usually metamorphosed to greenschist facies, and usually in Archaean-age terranes. |
| harzburgite |
A dark coloured ultramafic igneous intrusive rock composed of the minerals pyroxene and olivine. |
| hematite |
Mineral. Oxide ore of iron. |
| hydrothermal |
Pertaining to mineralising processes resulting from the circulation of hot water. |
| indicated resource |
A resource sampled by drillhole where scientific data is known with a reasonable level of confidence but drillholes are too widely spaced to ensure continuity. |
| inferred resource |
A resource scientific data is not known with a reasonable level of confidence and drillholes are too widely spaced to ensure continuity.
|
| intrusive |
Pertaining to igneous rocks emplaced into pre-existing rocks at depth. |
| IP survey |
Induced Polarization survey. An electrical geophysical survey technique measuring the magnetic field spontaneously induced in a
volume of rock by the application of an electric current. A technique often used to identify disseminated sulphide deposits. |
| ironstone |
Field term for iron-rich rocks the product of weathering. |
| JORC |
Joint Ore Reserves Committee. The guidelines of the JORC Code
(1999) are observed in the calculation of ore resources and ore
reserves. |
| komatiite |
Magnesium-rich mafic to ultramafic extrusive volcanic rock.
|
| lag |
Residual surficial material, comprising resistant fragments, such as quartz and ironstone. |
| lateritisation |
An extreme form of weathering common in tropical climates, in which silica an other constituents are removed, leaving a rock
characterised by a high proportion of alumina and/or iron oxide.
|
| layer-parallel fault |
A fault the plane of which lies parallel to the strata of the affected rocks. |
| leucogranite |
A granite composed almost entirely of light coloured minerals. |
| limonite |
Generic term applied to minerals comprising hydrated oxide of iron. Common constituent of weathered, ferruginous rocks. |
| lineament |
A large scale linear feature evident on aerial photography, satellite imagery or regional geophysical surveys. |
| lithology |
A term usually applied to sediments referring to their general characteristics. |
| Ma |
Million years ago. |
| mafic |
Descriptive of rocks composed dominantly of magnesium, iron and calcium-rich rock-forming silicates, and for rocks in which these
minerals are abundant. |
| magmatic |
Pertaining to molten rocks in the Earths crust. Precursor to igneous rocks. |
| magnesite |
Mineral. Magnesium carbonate. |
| magnetic anomalies |
Zones where the magnitude and orientation of the earth's magnetic field differs from adjacent areas. |
| magnetic survey |
Systematic collection of readings of the earth's magnetic field. |
| malachite |
Mineral. Carbonate ore of copper commonly found in the weathered portion of copper deposits. |
| marble |
Metamorphosed limestone. |
| Mesoproterozoic |
Middle Proterozoic era of geological time, 1,600 to 1,000 years ago. |
| mesothermal |
Mineral deposits formed (precipitated) at moderate temperatures. |
| metamorphic |
Pertaining to rocks altered by the action of heat and/or pressure. |
| metasediment |
Metamorphosed sediment. |
| metasomatised |
A metamorphic rock where material has been introduced from an external source during metamorphism. |
| migmatite |
A mixed rock comprising an original metamorphic rock extensively invaded by granitic material. |
| mineralisation |
The process of introduction of valuable elements into a rock body. Also a descriptive term for any body of economically valuable
minerals. |
| mineral resource |
A tonnage or volume of rock or mineralisation of intrinsic economic interest. |
| Mo |
Molybdenum. |
| molasse |
Thick sequences of sediments derived from the erosion of mountain ranges. |
| monzogranite |
A granular plutonic rock with a composition between monzonite and granite. |
| moraine |
An accumulation of sediment which has been transported and deposited by ice. |
| mylonite |
Very fine grained, usually foliated rock in elongate or linear zones caused by intense and prolonged shearing of the host rocks. |
| Neoproterozoic |
Late Proterozoic era of geological time, 1,000 to 570 million years ago. |
| Ni |
Nickel. |
| normal fault |
A fault along which movement has placed younger rocks over older rocks. |
| orogen |
A period of mountain building. |
| ortho- |
A prefix used in front of a metamorphic rock name indicating that rock derived from an igneous rock. Orthogneiss - gneissic rock
derived from igneous rock types. |
| palaeodrainage |
Ancient river system, possibly remnant only as sediments deposited in the original river. |
| Palaeoproterozoic |
Early Proterozoic era of geological time, 2,500 to 1,600 million years ago. |
| Pb |
Lead. |
| Pd |
Palladium. |
| pelite |
Metamorphosed argillite. |
| peneplanation |
The end process in the cycle of erosion usually resulting in a flat or near flat land surface. |
| PGE |
Platinum Group Elements, Platinum Group Metals: Platinum, Palladium, Iridium, Osmium, Rhodium and Ruthenium. Often associated with Ni-Cu iron-sulphides, and generally hosted by maficultramafic rock types. |
| Phanerozoic |
Geological period covering the time from the Cambrian (`600My bp) to 2My bp. |
| phyllite |
A cleaved metamorphic rock midway between slate and schist. |
| pisolite |
Approximately spherical accretion of iron or carbonate minerals. |
| plunge |
The attitude of a line in a plane, which is used to define the orientation of fold hinges, mineralised zones and other structures. |
| plutonic |
Granitic igneous mass approximately cylindrical in shape placed at a high level in the Earths crust. |
| polymetallic |
Containing many metals. |
| porcelainite |
A fine grained quartz rock having the appearance of porcelain. |
| ppb |
parts per billion. |
| ppm |
parts per million. |
| precious metal |
Gold, silver, PGE. |
| prehnite-pumpellyite |
Minerals the presence of which defines low-grade, sub-greenschist facies metamorphism. |
| primary |
A rock or mineral that has remained unaltered since it was originally formed. |
| Proterozoic |
Geological period from approximately 2,400My to 600My before present. |
| Pt |
Platinum. |
| pyrite |
Mineral. Iron sulphide. |
| pyrrhotite |
Mineral. Iron sulphide. |
| quartz |
Mineral. Silicon oxide. |
| quartzite |
Metamorphosed sandstone composed predominantly of recrystallised quartz. |
| quartzo-feldspathic |
Descriptive term for rock composed predominantly of near equal amounts of quartz and feldspar. |
| RAB |
Rotary Air Blast. A method of rotary drilling in which sample is returned, using compressed air, to the surface in the annulus between
drill-rod and the drill-hole. A relatively inexpensive and less accurate drilling technique. |
| radiometric |
Data relating to the radioactivity emitted by rocks at or near the earth's surface, usually collected by helicopter or fixed wing aircraft. |
| RC |
Reverse Circulation. A method of rotary drilling in which the sample is returned to the surface, using compressed air, inside the inner-tube of the drill-rod. A more accurate drilling technique than RAB, which minimises contamination. |
| regolith |
Generic name for all, usually unconsolidated, sediments covering and obscuring bedrock. |
| rift basin |
A large fault-bounded depression infilled with volcanic and/or sedimentary material. |
| saprolite |
Partially weathered rock usually with original primary rock textures retained. |
| Sb |
Antimony. |
| schist |
Regionally metamorphosed rock characterised by parallel arrangement of constituent minerals and usually exhibiting an undulose cleavage. |
| secondary |
A rock or mineral formed as a consequence of alteration, usually by oxidation, of pre-existing minerals. |
| SEDEX deposit |
A sediment-hosted massive sulphide deposit, typically tabular to lensoidal in shape and range from centimetres to tens of metres thick. Multiple horizons may occur over stratigraphic intervals of 1000 metres or more. Sedimentary exhalative deposits currently produce a significant proportion of the world's Zn and Pb. |
| sedimentary basin |
A depression of large size into which sediments have been deposited. |
| sericite |
Fine mica introduced through metamorphism or alteration. |
| shale |
A fine grained sedimentary rock usually with a well defined cleavage. |
| shear zone |
A zone in which rocks have been deformed primarily in a ductile manner in response to applied stress |
| sheetwash |
A widely distributed, thin blanket of sediment deposited in a broad, poorly defined drainage. |
| siliciclastic |
Sedimentary rock composed predominantly of quartz. |
| silicified |
Pertaining to a rock where silica has been introduced through the agency of metamorphism or weathering to form a very fine grained
quartz cement. |
| sill |
An igneous intrusive rock emplaced into sediments with the parallel margins of the intrusive parallel to the layering of the host sediments. |
| sphalerite |
Mineral. Sulphide ore of zinc. |
| stratiform |
Bedded or layered. |
| stratigraphy |
The study of formation, composition and correlation of sedimentary rocks. |
| strike |
The direction in which a horizontal line can be drawn on a plane. Usually used in describing the general trend of a rock layer or
structure. |
| stromatolite |
Ancient marine organism related to algae and forming distinctive fossil dome or columnar structures in sedimentary rocks. |
| subduction zone |
Refers to the area in which two crustal plates meet and, due to convergence, one is 'subducted' beneath the other. |
| sulphide |
A mineral in which a metal or metals exists in combination with sulphur. |
| supergene |
Of, or relating to minerals and mineral deposits or enrichments formed near the surface, generally by descending solutions. |
| supracrustal |
Pertaining to rocks created at the surface (sedimentary and volcanic rocks). |
| synform, syncline |
A basin-shaped fold. |
| syntectonic |
Occurring or forming at the same time as deformation and metamorphism. |
| tectonic |
An adjective used to relate a particular phenomenon to a structural or orogenic concept. |
| TEM survey |
Transient ElectroMagnetic survey - a variant of EM survey. |
| Tertiary |
The geological era from 65 million years to 0 million years before present. Often synonymous with Cainozoic. |
| tholeiitic |
A term applied to mafic or ultramafic rocks composed predominantly of magnesium-rich feldspar and pyroxene minerals. |
| tonalite |
A coarse grained plutonic rock similar to diorite in composition but containing quartz as 5% to 20% of the light coloured minerals.
tuff Usually fine grained volcanic ash. |
| turbidite |
Sediment deposited in a submarine environment from a gravitymobilised slurry. |
| ultramafic |
Igneous rocks consisting essentially of ferro-magnesium minerals and containing less than 45% silica, with trace quartz and feldspar. |
| unconformable |
A term recognising a break in sedimentation in a sedimentary sequence. |
| vein |
A tabular or sheet-like body of minerals, commonly quartz, injected into a fracture in pre-existing rocks. |
| VMS |
Volcanogenic Massive Sulphides. Mineral deposit formed by the exhalation of sulphide rich solutions and subsequent precipitation of sulphides onto the sea floor surrounding a hydrothermal vent. |
| volcanic |
Rock derived from volcanic activity - Usually lavas, tuffs or other volcanic debris. |
| volcaniclastic |
Pertaining to sedimentary clastic rock containing volcanic material. |
| wallrock |
The country rock of a vein or lode. |
| Zn |
Zinc |