Alcyone

Glossary

 

 

Terms not listed below are as defined in the Collins English Dictionary
(4th Australian Edition - ISBN 0 00 472219 1).

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.

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 assay value above which a mineral estimate is reorted.

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 (2004) are observed in the calculation of mineral 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 and 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 Earth’s 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.

pluton

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