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The source of metal and sulfur in VMS deposits is a combination of incompatible elements which are leached from the volcanic pile in the sub-seafloor hydrothermal alteration zone by hydrothermal circulation. Hydrothermal circulation is generally considered to be driven via heat in the crust often related to deep-seated gabbro intrusions.
Hydrothermal deposits of economically valuable and recoverable minerals are generally considered scarce, meaning such deposits are very small relative to the total area of earth's surface. [ 2 ] Each of these deposit types is usually considered to represent a distinctive deposit group with common features and in a similar four-dimensional ...
The source of platinum and palladium deposits is ultramafic rocks which have enough sulfur to form a sulfide mineral while the magma is still liquid. This sulfide mineral (usually pentlandite , pyrite , chalcopyrite , or pyrrhotite ) gains platinum by mixing with the bulk of the magma because platinum is chalcophile and is concentrated in sulfides.
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 ≤ 5–15% carbonate minerals, such as ankerite, dolomite and calcite. [16]
Massive sulfide deposits are ore deposits that have significant stratiform ore bodies consisting mainly of sulfide minerals.Most massive sulfide ore deposits have other portions that are not massive, including stringer or feeder zones beneath the massive parts that mostly consist of crosscutting veins and veinlets of sulfides in a matrix of pervasively altered host rock and gangue.
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 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 ]