Glossary Of Terms



Abbreviations (quantitative)

g/t grams per tonne, Ha hectare, km kilometre, km2  square kilometre, koz kilo ounces, kt – kilo tonnes, m – metre, m3  cubic metres, M – million, Ma – million years ago, Mt – million tonnes, Mtpa – million tonnes per annum, oz – ounces, ppm – parts per million, ppb – parts per billion, % percentage, t tonnes, tpd tonnes per day, t/m3  tonnes per cubic metre.

Abbreviations (common chemical)

As – arsenic, Ag – silver, Au gold, Cu copper, Fe – iron, Mg – magnesium, Mo molybdenum, Ni nickel, Pb – lead, Sb antimony, W tungsten, Zn – Zinc.

3D geological model

Computerised representation of the geology, incorporating stratigraphy, structures, and other important geological features.


Era of the geological time scale within the Precambrian aeon containing rocks greater than 2500 million years old.

aeromagnetic (survey)

A geophysical exploration technique where variations in the earth’s magnetic field reflecting magnetic mineral content of different rocks are measured using sensors on an aeroplane or drone.

aircore drilling

Drilling method that uses a triple blade cutting bit typically made of steel or tungsten on drilling rods that have an inner and an outer tube. Provides improved sample quality on cheap percussion methods (refer ‘Rotary air blast drilling’) as compressed air pumped down the outer tube returns the sample material to the surface through the inner tube, minimising sample cross-contamination. This method is capable of boring unconsolidated or soft weathered material only, and reachable depths are limited by the machine’s available air pressure, so it is traditionally used in first pass exploratory phases.


Describes sedimentary processes, or products of sedimentary processes involving water.

alluvial gold

An accumulation of alluvium (sediment), including gold fragments, in the bed or former bed of a river.

aqua regia

A geochemical analysis method where a mineral sample is digested in mixture of nitric and hydrochloric acids (‘aqua regia’) prior to ICP-OES or ICP-MS scanning. Commonly used in greenfields exploration for gold, platinum and many base metals. It is relatively inexpensive, can detect gold to as low as 0.1 ppb, and most oxide, sulphide and carbonate minerals are digested. As a partial leach, it will leave an undigested silicate and alumina residue, which may impact gold digestion if caught within the residue component matrices.


The process of determining the relative concentration of elements or compounds of a sample of material from the earth, through a range of physical or chemical techniques.

banded iron formation (BIF)

Iron formation that shows banding, generally of iron-rich minerals and chert or fine-grained quartz.


A fine -grained igneous rock consisting mostly of plagioclase feldspar and pyroxene.

base metals

Non-precious metals including copper, lead, nickel, or zinc.


Large low-lying area, often below sea level, in which sediments collect.

basin (sedimentary)

Refers to any geographical feature exhibiting subsidence (downward shift) and consequent infilling by sedimentation.


Bulk Leach Extractable Gold; a geochemical analysis method that uses cold cyanide solution to digest a large sample (typically 2 kg) and determine gold content through solvent extraction. Commonly used in greenfields exploration where gold content is unknown as detection limits are as low as 0.1 ppb. It is not a total gold extraction method, but bulk assay can overcome issues relating to ‘nugget effect’.

block model

A model comprising rectangular blocks, each with attributes such as grades, rock types, codes that represents a given mineral deposit.


A fragmental rock where large angular clasts are supported in a finer grained matrix. They may form in sedimentary, volcanic, or tectonic environments. Fragment angularity indicate the breccia formed close to the source of those fragments.


Describes exploration that is near existing mine infrastructure (see also ‘greenfields’).

buckshot (pyrite)

A large, rounded pyrite grain or accumulation of grains formed by reworking of pyrite of sedimentary or diagenetic origin.

bulk density

A property of particulate materials. It is the mass of many particles of the material divided by the volume they occupy. The volume includes the space between particles as well as the space inside the pores of individual particles.


Describing rock composed of fragments or particles of older rocks.


Loose, unconsolidated sediments that have been deposited at the base of hillslopes by either rain, sheetwash, slow continuous downslope creep, or a variable combination of these processes


The end product of crushing, grinding, and flotation processes.


A detrital sedimentary rock composed of rounded to sub-angular shaped fragments, which have a particle size of greater than 2 mm, surrounded by fine grained matrix.


A surface which separates one rock type from another.


See diamond drilling.


A trench dug either by hand or mechanical excavation equipment to allow collection of geological data and mineral samples from sub-surface.


A large, stable block of the earth’s continental crust.

cut-off grade

The grade that differentiates between mineralised material that is economic to mine and material that is not.


A mechanical collection device, usually on a drilling rig, that separates rock particles from air using vortex separation.


Term used to describe changes in rocks after their formation, usually caused by tectonic forces.

diamond drilling (DD)

Drilling method that uses a rotating bit encrusted with industrial diamonds to cut a cylinder of rock. The rock cylinders are returned to the surface by pulling the steel casing containing the cylinder via mechanical pulley. The rock pieces are laid into trays in order. This method is the most expensive of the drilling types but also produces the most representative sample and as such is used at advanced project stages. Drilling fluids may be used.


Geological measurement the angle at which bedding, or a structure is inclined from the horizontal.


A homogenous zone within a mineral deposit consisting of a single grade population, orientation of mineralisation and geological texture.


A means of cutting into the earth by machinery equipped with metal rods and a cutting tool (‘bit’), usually for the purposes of bringing rock and/or regolith samples from underground to the surface. (Refer aircore, diamond, rotary air blast and reverse circulation drilling.)


A tabular igneous intrusive rock that cuts across the bedding or foliation of the country rock.

electromagnetic/ EM (survey)

A geophysical exploration technique that measures the propagation of electromagnetic fields by passing an alternating electric current through a coil of wire either mounted on an aircraft or placed over the ground. Commonly used to search for conductive bodies such as sulphide deposits.
VTEM (‘Versatile Time-Domain EM’) is a proprietary EM survey technology that measures signal changes with time and can discriminate between moderate to excellent conductors.


Describing igneous rocks rich in light-coloured silicate minerals, such as feldspar, quartz, and muscovite. Also describes the magma from which felsic rocks are derived. Colloquially used as a noun interchangeably with ‘felsic rock’.

fire assay

A geochemical analysis method that determines element quantities by separating metals from impurities using fusion processes. Commonly used in quantifying gold, silver, platinum, and palladium in exploration mineral samples.


The underlying side of a fault, orebody or mine workings.


A coarse-grained, dense, mafic intrusive rock comprising pyroxene, plagioclase feldspar, and often olivine.


The science of determining the age and history of rocks and geological events.


A generic term for information determined by observing the mechanical properties of rocks.

gold characterisation study

A study designed to determine the nature (size, shape and deportment) of gold particles in a given rock type; and ultimately used to calculate the minimum sample size necessary for accurate gold content determination.

grade cap (top cut)

Restriction of the influence of very high grades, designed to avoid over smoothing of these grades into too large an area.

grade control

The process of collecting geological, sample and assay information for the delineation of mineable ore boundaries; the minimization of dilution and ore loss, and the reconciliation of the predicted grade and tonnage to the grade and tonnage mined and milled.


A coarse-grained, intrusive igneous rock composed mainly of quartz and feldspar.


Describing a system of blocks, or ‘graticules’ defined by a network of meridian and parallel lines. Decreasing longitudinal distance between meridians away from the equator mean block areas also decrease towards the poles. In Western Australia, most blocks are approximately 3 km2.


Describes exploration that is not near existing mine infrastructure (see also ‘brownfields’).


Generic term for belts of volcanic and associated sedimentary rock typically occurring between granite plutons in Archaean and Proterozoic cratons.


The overlying side of a fault, orebody or mine workings.


Describes rock formed through the cooling and solidification of magma or lava.

Indicated Mineral Resource

‘An ‘Indicated Mineral Resource’ is that part of a Mineral Resource for which tonnage, densities, shape, physical characteristics, grade and mineral content can be estimated with a reasonable level of confidence. It is based on exploration, sampling and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes. The locations are too widely or inappropriately spaced to confirm geological and/or grade continuity but are spaced closely enough for continuity to be assumed.’

Induced Polarisation/ IP

A geophysical exploration technique that measures the electrical chargeability of rocks by passing current through two electrodes inserted into the ground, switching the current off, and then measuring the voltage decay from the stored charge in rock minerals. Commonly used to find disseminated sulphide ore.

Inferred Mineral Resource

‘An ‘Inferred Mineral Resource’ is that part of a Mineral Resource for which tonnage, grade and mineral content can be estimated with a low level of confidence. It is inferred from geological evidence and assumed but not verified geological and/or grade continuity. It is based on information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings, and drill holes which may be limited or of uncertain quality and reliability.’


An igneous body of rock that forms when magma rises slowly, either by exploiting pre-existing rock weakness such as faults or pushing existing rock away by cracking or melting, creating space into which it can intrude. The body cools and solidifies underground, usually slowly enough to create macrocrystalline textures e.g. granite.


Describing a rock that has intruded older rock (see ‘intrusion’). Colloquially used as a noun interchangeably with ‘intrusion’.

inverse distance estimation

A method for interpolation, which assigns values to unknown points by using values from a set of known points. The value at the unknown point is a weighted sum of the values of the known points.


The JORC Code is an Australian reporting code which is applicable for companies listed on the Australian Securities Exchange. It provides minimum standards for public reporting to ensure that investors and their advisers have all the information they would reasonably require for forming a reliable opinion on the results and estimates being reported. The current version is dated 2012.


A geostatistical estimation method using a distance weighting technique which is based upon the relative spatial continuity of the samples.


A geochemical analysis method that uses an accelerant during cyanide leaching to determine the cyanide extractable gold content, providing an indicator of potential metallurgical recoveries. Subsequent analysis of sample residue can provide both a ‘total gold’ value and the refractory component of the sample.


Of unconsolidated sediment: to harden and become rock.


The study and description of rocks, including their mineral composition and texture.


Ore zone.

long hole open stoping (LHOS)

Underground mining method comprising the extraction of ore from stopes which are charged up from drillholes put in from one or more elevations within the stope.


Describes silicate minerals, magma, and volcanic and intrusive igneous rocks that have relatively high concentrations of the heavier and darker minerals. Colloquially used as a noun interchangeably with ‘mafic rock’.

magnetic anomaly (high / low)

Magnetic signatures different from the background, made up of a high and a low (dipole) compared to the average field.

Measured Mineral Resource

‘A ‘Measured Mineral Resource’ is that part of a Mineral Resource for which tonnage, densities, shape, physical characteristics, grade, and mineral content can be estimated with a high level of confidence. It is based on detailed and reliable exploration, sampling and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings, and drill holes. The locations are spaced closely enough to confirm geological and grade continuity.’


Study of the physical properties of metals as affected by composition, mechanical working and heat treatment.


Describes sedimentary rock that shows evidence of having been subjected to metamorphism.


Where minerals accumulate in sufficient quantity to be considered potentially economic.

mineralisation solid

See wireframe.


Describing sedimentary rocks, usually breccia, where the clast component comprises only one rock type.

National Instrument 43-101

National Instrument 43-101 Standards of Disclosure for Mineral Projects forms part of Canadian securities legislation and is applicable for companies which are deemed to be “reporting issuers” in Canada or listed on a Canadian stock exchange, including the Canadian Securities Exchange, TSX Venture Exchange, Toronto Stock Exchange, and the NEO Exchange. In conjunction with other Canadian securities legislation, 43-101 provides minimum standards for public reporting to ensure that investors and their advisers have all the information they would reasonably require for forming a reliable opinion on the results and estimates being reported. 43-101 was last updated in 2016.

Native Title (Australia)

The recognition by Australian law of rights and interests to land and waters held by Aboriginal or Torres Strait Islander peoples under their traditional laws and customs. Native Title is governed by the Native Title Act (1993).

nugget effect

The random component of the grade variability due to irregular distribution of the metal of interest. Nugget effect is common in gold deposits where mechanical or regolith processes have concentrated coarse gold particles randomly within a lower grade envelope.

Ore Reserve

‘An ‘Ore Reserve’ is the economically mineable part of a Measured and/or Indicated Mineral Resource. It includes diluting materials and allowances for losses, which may occur when the material is mined. Appropriate assessments and studies have been carried out and include consideration of and modification by realistically assumed mining, metallurgical, economic, marketing, legal, environmental, social, and governmental factors. These assessments demonstrate at the time of reporting that extraction could reasonably be justified. Ore Reserves are sub-divided in order of increasing confidence into Probable Ore Reserves and Proved Ore Reserves.’

ore sorter

Material sorting equipment engineered to separate mineralised material from non-mineralised material using sensor sorting technology. Sensor types include X-ray transmission, laser, near-infrared, colour scanning, and electromagnetic technology. Ore sorters are used to produce a higher-grade concentrate prior to ore recovery processing.


The process of mountain-building during periods of tectonic activity, and deformation imposed on rocks during that event.


Describing tectonic forces that result in large scale deformation of portions of the earth’s crust.


Material that lies on a mineral deposit or other feature of interest. Commonly refers to surficial soil or sand that must be removed to exploit mineralised rock beneath.

oxidation, oxidised

The addition of oxygen to the metal ion, generally as a result of weathering.

percussion drilling

A drilling method that raises and drops a large hammer bit in a hole to break and recover material at the face.

Photon Assay

An analysis method developed by CSIRO employees and now is proprietary technology under Chrysos Corp. The method uses X-ray activation to measure gold content quickly, accurately, chemical-free, and non-destructively. A bar-coded jar is filled with sample material, placed on a conveyor and hit with high-powered X-rays to excite the nuclei of any gold atoms present. Detectors record the unique signatures from the activated atoms, giving the sample’s gold concentration.


A type of foliated metamorphic rock primarily composed of quartz, sericite mica, and chlorite.


A type of river or lake sediment that contains particles of economic minerals, e.g. gold. ‘Palaeoplacer’ refers to a lithified, ancient placer deposit.


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


Describing sedimentary rocks, usually conglomerate, where the clast component comprises more than one rock type.


Era of the geological time scale within the Precambrian eon containing rocks of approximately 1000 2500 million years old.


An ideally representative crushed and homogenous sub sample of an original mineral sample.

pXRF (portable XRF)

A portable, handheld device that uses X-ray fluorescence to measure elemental composition of sample material. The device’s X-rays bombard the sample causing elements within it to in turn emit their own X-rays: the wavelengths and energies of which are characteristic of the element from which they came. The intensity of the X-ray returned is related to the concentration of that element so allows quantitative measurement. Limitations relating to elements that emit very similar energies, such as gold vs arsenic, tungsten and lead mean false readings should be considered.


Quality Assurance/ Quality Control; a set of tests that check for accuracy, precision and lack of bias in assaying, grade, and other measurements.


The maximum distance within which a set of grades are correlated with itself.


Describing ore; accessory minerals in ore, commonly sulphide minerals, render gold extraction via conventional leaching poorly effective due to occlusion of gold within those minerals.


The layer of unconsolidated material that sits above bedrock. Includes transported soil and gravel material and the weathered component of in-situ rock.


The material that remains after mineral sample is analysed.  Or in the case of plant-processed material, what is left after test work, generally tailings with most of the critical metal or mineral removed.

reverse circulation drilling (RC)

A drilling method that forces compressed air down an outer drill tube to where a hydraulic hammer breaks the rock face and blows the broken chips back up an inner tube to the surface. This method generally produces more reliably uncontaminated samples than either RAB or aircore drilling, but at higher cost and is therefore frequently used at an advanced exploration phase of project development.

rotary air blast drilling (RAB)

A cheap and quick drilling method using a rotating blade bit on single tube rods together with air pressure to produce rock chips for sampling. Sample quality is generally poorer than other drilling methods due to downhole contamination potential. It is used at the early exploration stages of project evaluation.


A sedimentary rock composed of sandsized particles.


A type of granitoid with specific felsic to intermediate composition range, typically rich in K-feldspar and mafic minerals. Most were emplaced across the Archaean – Proterozoic earth history transition.


Medium-grade metamorphic rock, that exhibits ‘schistosity’, that is, a texture that develops when platy minerals such as mica, chlorite, talc, hornblende and graphite align forming layers.

screen fire assay

A geochemical analysis method that analyses coarse and fine component of a sample separately and produces a weighted average of the two components for an overall grade. Frequently used when coarse gold particles are anticipated as it generates a ‘total gold’ value of the sample. See also ‘fire assay’.


An independent geologist employed to oversee the sampling process to monitor chain of custody and maintain sample integrity.


Rock forming process where material is derived from pre-existing rocks by weathering and erosion.


Type of fault or the act of deforming rock via applied stresses.

shear zone

A shear zone is a tabular to sheet like, planar or curviplanar zone composed of rocks that are more highly strained than the rocks adjacent to the zone. Typically, this is a type of fault, and may form zones of much more intense foliation, deformation, and folding. En echelon veins or fractures may be observed within shear zones.


A detrital sedimentary rock composed of clay minerals with a wellmarked bedding plane usually due to the alignment of the clay minerals.


A detrital sedimentary rock composed of clay minerals similar to mudstone but with mostly silt-grade material (1/16 to 1/256) mm.


A sequence of rock units deposited during a particular period.


Geological measurement the direction of bearing of bedding or structure in the horizontal plane.


Compound containing sulphur and another element, commonly an economic metal such as copper, lead, iron, zinc.


The residue from a mineral processing plant; generally pulverised waste rock.

test work

A generic term for a wide range of metallurgical tests applied to rock samples designed to predict the performance of a processing plant.

thrust fault

A type of reverse fault where the fault plane slopes at a very low angle.

top cut

A process that reduces the effect of isolated (and possible unrepresentative) outlier assay values on the estimation.


The partially oxidised zone between oxidized and fresh material.


See ‘costean’.


A rock formed from volcanic ash and other debris products of an explosive volcanic eruption.


A sedimentary rock deposited by a turbidity current.

turbidity current

A rapid, downhill gravity flow of water and sediment. Turbidity currents can be caused by earthquakes, collapsing slopes, and other geological disturbances. They are responsible for distributing vast amounts of unconsolidated clastic sediment into the deep ocean.


Describing igneous rocks with very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium and are composed of usually greater than 90% mafic minerals.


A surface in a rock sequence that marks a notable hiatus in time between two periods of deposition.


Definition of the three-dimensional grade continuity of drillhole samples by estimating and modelling the relationship between grade similarity and distance in every direction and at every sample spacing.


A tabular or sheet like body of one or more minerals deposited in openings of fissures, joints, or faults.


A small or secondary vein.


Describing an igneous rock of volcanic origin.


Describing a rock partly or entirely composed of volcanic fragments and deposited by mechanical means, such as water lain or gravity deposition.


See ‘Electromagnetic/ EM’

Wacke / greywacke

A poorly sorted sandstone containing fragments of rock and minerals in a clayey matrix


A surface or 3D volume formed by linking points together to form triangles. Wireframes are used in the construction of block models.