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The hydrothermal fluid leaches metals as it descends and precipitates minerals as it rises. Sedimentary exhalative deposits, also called sedex deposits, are lead-zinc sulfide deposits formed in intracratonic sedimentary basins by the submarine venting of hydrothermal fluids. These deposits are typically hosted in shale.
These deposits are also sometimes called volcanic-hosted massive sulfide (VHMS) deposits. The density generally is 4500 kg/m 3 . They are predominantly stratiform accumulations of sulfide minerals that precipitate from hydrothermal fluids on or below the seafloor in a wide range of ancient and modern geological settings.
Different mineral associations precipitate during the typical stages of mineralization that characterize the life span of such systems. [1] [2] [3] Minerals present in a hydrothermal system or a fossil volcanogenic massive sulfide deposit are deposited passively or reactively.
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]
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 .
Epithermal — mineral ore deposits formed at low temperatures (50–200 °C) near the Earth's surface (<1500 m), that fill veins, breccias, and stockworks. [2] Telethermal — mineral ore deposits formed at shallow depth and relatively low temperatures, with little or no wall-rock alteration, presumably far from the source of hydrothermal ...
Sphalerite is amongst the most common sulfide minerals, and it is found worldwide and in a variety of deposit types. [8] The reason for the wide distribution of sphalerite is that it appears in many types of deposits; it is found in skarns , [ 25 ] hydrothermal deposits , [ 26 ] sedimentary beds, [ 27 ] volcanogenic massive sulfide deposits ...
Main ore minerals in SEDEX deposits are fine-grained sphalerite and galena, chalcopyrite is significant in some deposits; silver-bearing sulfosalts are frequent minor constituents; pyrite is always present and can be a minor component or the dominant sulfide, as it is the case in massive sulfide bodies; barite content is common to absent ...