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In situ gold-bearing vein (in brown) at the Toi gold mine, Japan. In many gold mines exploited during the gold rushes of the 19th century, vein material alone was typically sought as ore material. [8] In most of today's mines, ore material is primarily composed of the veins and some component of the wall rocks which surrounds the veins. [9]
"Mining on the Comstock", depicts the headframes and mills of the various mines, and the mining technology used at Comstock, most prominently the method of square-set timbering developed there to work the veins. Comstock Lode geologic map, north. Ophir is in the top center; "qz" is quartz and signifies the Comstock Lode. [1]:
Along an ore shoot, there is a rich gathering of different minerals within a vein. The veins can resemble a pipe, chimney or ribbon in structure and are displaced mainly vertically oriented but also can be horizontal with large veins extending approximately 30 m (100 ft) horizontally and 150 m (500 ft) vertically. [3]
Hushing is an ancient and historic mining method using a flood or torrent of water to reveal mineral veins. [1] [2] The method was applied in several ways, both in prospecting for ores, and for their exploitation. Mineral veins are often hidden below soil and sub-soil, which must be stripped away to discover the ore veins.
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.
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.
During this working period, nearly 200,000 tons of ore were removed, yielding 3,500 tons of copper metal. The mines closed in 1877 and the Abandonment Plan of 1878 shows all the workings open at that date. This period saw the mining of West Mine and Wood Mine and the reworking of Engine Vein, Brynlow, Doc Mine and other smaller mines on the Edge.
Cartoon cross-section showing manto ore deposits (USGS) [1] A polymetallic replacement deposit, also known as carbonate replacement deposit or high-temperature carbonate-hosted Ag-Pb-Zn deposit, [2] is an orebody of metallic minerals formed by the replacement of sedimentary, usually carbonate rock, by metal-bearing solutions in the vicinity of igneous intrusions. [3]