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. |
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