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Hydrothermal mineral deposits are accumulations of valuable minerals which formed from hot waters circulating in Earth's crust through fractures. They eventually produce metallic -rich fluids concentrated in a selected volume of rock, which become supersaturated and then precipitate ore minerals.
Hydrothermal gold in quartz (white mineral) vein with other gangue minerals (black minerals). Geochemical studies on gold bearing quartz-carbonate veins are important to determine temperature, pressure, at which the veins were generated, and the chemical signature of fluids. Quartz is generally the dominant mineral in the veins, but there are ...
The Mount Isa orebody, located in Queensland, Australia, is an excellent example. [109] Many hydrothermal vents are rich in cobalt, gold, copper, and rare earth metals essential for electronic components. [110] Hydrothermal venting on the Archean seafloor is considered to have formed Algoma-type banded iron formations, which have been a source ...
The source of the heating for the water in the hydrothermal circulation is still under discussion. [4] The material in the deposit is altered in a way that the carbonate minerals are either dissolved or converted to the silicates by silicate rich hydrothermal water. For example, dolomite is transformed into jasperoid.
The content of gold within these deposits is largely variable, and can be a factor in the economic value of the deposit. The gold contents of all deposits averages 0.41 g/t Au, with the majority of worldwide deposits averaging less than 1 g/t Au. [2] The occurrence of native gold mineralization. Example from Kalgoorlie Australia.
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.
Veins formed in this way may exhibit a colloform, agate-like habit, of sequential selvages of minerals which radiate out from nucleation points on the vein walls and appear to fill up the available open space. Often evidence of fluid boiling is present. Vugs, cavities and geodes are all examples of open-space filling phenomena in hydrothermal ...
Sedimentary exhalative deposits (SEDEX or SedEx deposits) are zinc-lead deposits originally interpreted to have been formed by discharge of metal-bearing basinal fluids onto the seafloor resulting in the precipitation of mainly stratiform ore, often with thin laminations of sulfide minerals.