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A quartz vein, prominent from the surrounding weathered rock at Cape Jervis, South Australia. Open space filling is the hallmark of epithermal vein systems, such as a stockwork, in greisens or in certain skarn environments.
Gold drew the attention of gold prospectors as early as 1886, [6] and in 1899 a vein of goldbearing quartz was discovered which raised hopes for the further expansion of gold mining activities in the South-East of Australia. [7] However, the search quickly turned to the discovery of petroleum between Lake Albert station and Didicoolum station. [8]
One of the largest silver lodes was the Comstock Lode in Nevada, [6] although it is overshadowed by the more recently discovered Cannington Lode in Queensland, Australia. [7] [8] The largest gold lode in the United States was the Homestake Lode. [9] The Broken Hill Lode in South Australia is the largest lead-zinc lode ever discovered. [10]
Quartz reef breaking the surface at Paynes Find, Western Australia. Quartz reef mining is a type of gold mining in "reefs" (veins [1]) of quartz.Quartz is one of the most common minerals in the Earth's crust, and most quartz veins do not carry gold, but those that have gold are avidly hunted by prospectors.
Quartz is generally the dominant mineral in the veins, but there are also gold bearing carbonate dominant veins in orogenic deposits. [15] Ore bodies of orogenic gold deposits are generally defined by ≤ 3–5% sulfide minerals, most commonly arsenopyrite in metasedimentary host rocks and pyrite /pyrrhotite in meta-igneous rocks, and ≤ 5 ...
Granite (light) with sheeted veins of greisen (dark) at Cligga Head, Cornwall. Greisen is a highly altered granitic rock or pegmatite, usually composed predominantly of quartz and micas (mostly muscovite). Greisen is formed by self-generated alteration of a granite and is a class of moderate- to high-temperature magmatic-hydrothermal alteration ...
Quartzolite or silexite is an intrusive igneous rock, in which the mineral quartz is more than 90% of the rock's felsic mineral content, with feldspar at up to 10%. [ 1 ] : 135 [ 2 ] Typically, quartz forms more than 60% of the rock, [ 3 ] the rest being mostly feldspar although minor amounts of mica or amphibole may also be present. [ 2 ]
Hydrothermal vein ore deposits consist of discrete veins or groups of closely spaced veins. Veins are believed to be precipitated by hydrothermal solutions travelling along discontinuities in a rockmass. [10] They are commonly epithermal in origin, that is to say they form at relatively high crustal levels and moderate to low temperatures.