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mineral is a naturally
occurring solid formed through geological processes that has a characteristic
chemical composition, a highly ordered atomic structure, and specific
physical properties. A rock, by comparison, is an aggregate of
minerals and/or mineraloids, and need not have a specific
chemical composition. Minerals range in composition from pure elements and
simple salts
to very complex silicates with
thousands of known forms.[1] The
study of minerals is called mineralogy Sulfate minerals all contain the sulfate anion, SO42-. Sulfates commonly form in evaporitic settings where highly saline waters slowly evaporate, allowing the formation of both sulfates and halides at the water-sediment interface. Sulfates also occur in hydrothermal vein systems as gangue minerals along with sulfide ore minerals. Another occurrence is as secondary oxidation products of original sulfide minerals. Common sulfates include anhydrite (calcium sulfate), celestine (strontium sulfate), barite (barium sulfate), and gypsum (hydrated calcium sulfate). The sulfate class also includes the chromate, molybdate, selenate, sulfite, tellurate, and tungstate minerals |