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An orogenic gold deposit is a type of hydrothermal mineral deposit. ... In magmatic systems, ores and host rocks are derived from the same fluid. [11]
High-grade gold ore from the Harvard Mine, Jamestown, California, a wide quartz-gold vein in California's Mother Lode.Specimen is 3.2 cm (1.3 in) wide. Various theories of ore genesis explain how the various types of mineral deposits form within Earth's crust.
Ascending hydrothermal solutions rich in gold, sulfur and metals were channelled upward along major fracture and fault zones. Fluid that made it to the surface would have vented as hot springs and geysers. Localized erosion through the thrust sheet has formed windows into the underlying ore-bearing rocks. Adapted from Edwards and Atkinson (1985).
The Reko Diq Mine is a planned mining operation, located near Reko Diq town in Chagai District, Baluchistan, Pakistan. [1] Reko Diq represents one of the largest copper and gold reserves in the world having estimated reserves of 5.9 billion tonnes of ore grading 0.41% copper and gold reserves amounting to 41.5 million oz, and a mining life of at least 40 years.
Carlin-type gold ore from the Twin Creeks mine, Nevada, near the Getchell Mine. This is an auriferous, silicified-decalcified siltstone/mudstone from the Comus Formation (Lower Ordovician). Ore grade is about 0.20 to 0.25 ounces of gold per ton of rock. The gold mineralization is very finely disseminated: "invisible gold".
Deposits of this class have been classified by numerous workers in different ways (e.g., metal sources, type examples, geodynamic setting – see Franklin et al. (1981) and Lydon (1984)). The magmatic assemblages of VMS deposits are associated with varying tectonic settings and geological environments during the formation of the VMS.
Iron oxide copper gold (IOCG) deposits are considered to be metasomatic expressions of large crustal-scale alteration events driven by intrusive activity. The deposit type was first recognised by discovery and study of the supergiant Olympic Dam copper-gold-uranium deposit (Olympic Dam mine), and South American examples.
Like most Carlin type gold deposits in Nevada the gold was epithermally deposited in carbonate or silicate sedimentary rocks. The heat source was magmatic but the exact mechanism is still under debate. The Betze-Post deposits are up to 6,000 feet (1,800 m) long, 600 feet (180 m) thick and 800 feet (240 m) wide.