SolGold RNS Glossary

Alteration

Changes in the chemical or mineralogical composition of the rock, usually produced by hydrothermal

solutions or weathering

A-Vein

An early generation of vein in porphyry copper deposits that form whilst the rock is extremely hot and partly ductile. Ductile deformation of the solidifying magma produces contorted and segmented (worm-like) vein textures. These are high temperature veins and can host substantial copper sulphide minerals in association with quartz.

Bornite

Copper-iron sulphide (Cu5FeS4). An ore of copper occasionally associated with chalcopyrite or chalcocite. Oxidise rapidly at surface (within minutes) to a purple-blue iridescence.

B-Vein

A particular generation of abundant quartz stockwork veins in porphyry copper deposits

characterised by quartz fill and crack-seal textures. B-veins are often lined with copper-sulphide minerals along the centreline of the vein, and also locally along the margins of the vein.

Chalcocite

Black or dark grey copper sulphide mineral (Cu2S). Chalcocite is an important ore mineral of copper, often occurring as a result of secondary enrichment (oxidation and weathering).

Chalcopyrite

Brassy or golden-yellow ore mineral of copper (CuFeS2). The most common ore mineral of copper.

Chargeability

The ability of earth materials to hold a charge for an extended period of time.

Conductivity

The ability of a material to conduct electrical current. In isotropic material, it is the reciprocal of

resistivity. Units are Siemens/m.

C-Vein

A particular (abundant) generation of stockwork veins in porphyry copper deposits characterised by

monomineralic sulphides. E.g. a vein comprising of only chalcopyrite, or of only bornite. C-veins generally form later than B-veins and typically cross-cut or re-open earlier B-veins.

Dickite

A crystallised clay mineral of the kaolin group, having the same composition Al2Si2O5(OH)4. It forms at relatively high temperature by alteration of feldspar caused by strongly acidic hydrothermal fluids.

Hydrothermal

Of or pertaining to heated water, to its actions, or its products.

Induced Polarisation (IP)

Induced Polarisation (IP) is a technique of measuring an induced potential field in the ground in order

to map the geological subsurface. From measurements of the induced potential field the

chargeability and resistivity of the subsurface can be calculated. These measurements are made in either the time domain or frequency domain using various configurations of transmission electrodes and multiple potentiometer receivers.

Intrusive

A body of magma emplaced into a rock and then solidified upon cooling.

Isosurface

A 3 dimensional surface linking all points of equal value.

Lithocap

A shallow region of intense silica and clay hydrothermal alteration that commonly occurs over

porphyry Cu-Au deposits

Magnetite

A strongly magnetic shiny black iron-oxide mineral - (Fe,Mg)Fe2O4.

Magnetic Vector Inversion

A recently developed geophysical computational technique for modelling magnetic field data.

Magnetotelluric

An electromagnetic geophysical method for inferring the earth's subsurface electrical conductivity

from measurements of natural geomagnetic and geoelectric field variation at the Earth's surface.

Investigation depth ranges from 300m below ground by recording higher frequencies down to

10,000m or deeper with long-period soundings. Developed in the USSR and France during the 1950s, MT is now an international academic discipline and is used in exploration surveys around the world

Metallurgy

The science that deals with procedures used in extracting metals from their ores and purifying

metals.

Pathfinder Element

Elements that occur in minor or trace quantities in association with the main ore elements, and can

be used in exploration as indicators of the presence of nearby mineralisation.

e.g. As, Sb, Tl, Hg and Te are pathfinder elements for epithermal Au-Ag +/- Cu deposits that occur at high levels above porphyry Cu-Au deposits.

Porphyry Cu

Copper orebodies that are formed from hydrothermal fluids that originate from a voluminous magma

chamber several kilometres below the deposit itself. Predating or associated with those fluids are

vertical dikes of porphyritic intrusive rocks from which this deposit type derives its name.

Pyrophyllite

A yellowish-white clay-like mineral - AlSi2O5(OH). Formed at high temperature and from very acidic hydrothermal fluids which leach Ca, Na, K, Mg and other elements from the rock and leave the most immobile elements Al and Si in the new alteration minerals.

Resistivity

Resistivity is an active geophysical technique that uses probes to introduce an electrical current into

the ground, measuring the resistance of the rocks to the passage of an electric current.

Secondary Magnetite

Magnetite formed by hydrothermal processes as opposed to primary magnetite that crystallise

directly from a magma.

Sheeted Veins

Vein sets where most of the veins are broadly parallel and close-spaced. These often occur in or near

to fault zones.

Stockwork Veins

Vein sets which have multiple orientations.

distributed by