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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.
Volcanogenic massive sulfide ore deposits, also known as VMS ore deposits, are a type of metal sulfide ore deposit, mainly copper-zinc which are associated with and produced by volcanic-associated hydrothermal events in submarine environments. [2] [3] [4] These deposits are also sometimes called volcanic-hosted massive sulfide (VHMS) deposits
The sulphide minerals are a class of minerals containing sulphide (S 2−) or disulphide (S 2− 2) as the major anion. Some sulfide minerals are economically important as metal ores . The sulphide class also includes the selenides , the tellurides , the arsenides , the antimonides , the bismuthinides, the sulpharsenides and the sulphosalts .
Eventually a point is reached where the minerals start to crystallise out. [2] Minerals formed in this way are called primary, or hypogene, minerals. Sulfur is a common component of the fluids, and most of the common ore metals, lead , zinc , copper , silver , molybdenum and mercury , occur chiefly as sulfide and sulfosalt minerals. [ 3 ]
Classification of hydrothermal ore deposits is also achieved by classifying according to the temperature of formation, which roughly also correlates with particular mineralising fluids, mineral associations and structural styles. [2] This scheme, proposed by Waldemar Lindgren (1933) classified hydrothermal deposits as follows: [2]
The ore fluids of MVT deposits are typically low temperature (100 °C–150 °C) and have the composition of basinal brines (10–30 wt.% NaCl equivalent) with pH's of 4.5–5 (buffered by host carbonates). This hydrothermal fluid may or may not carry the required sulfur to form sulfide minerals.
The three main families of sulfide polymetallic ores are identified as volcanogenic massive sulphide family, the sedimentary exhalative family, and the Mississippi Valley type family. The classification of lead-zinc deposits in particular has been varied and resulted in a number of different organizations schemes. [ 1 ]
A sulfide deposit is an ore body or rock containing a great deal of sulfide minerals. Articles on this topic include: Seafloor massive sulfide deposits; Sedimentary exhalative deposits; Volcanogenic massive sulfide ore deposit; Massive sulfide deposits