Sulfate mineral

A mineral whose crystal structure contains the sulfate anion, SO₄²⁻, commonly combined with metal cations or water. Sulfate minerals include both anhydrous and hydrated forms.

Sulfate: The polyatomic anion SO₄²⁻, consisting of one sulfur atom bonded to four oxygen atoms. This anion is the defining structural unit shared by all sulfate minerals.
Gypsum: A hydrated calcium sulfate mineral with the formula CaSO₄·2H₂O. Gypsum is a common hydrated sulfate and a major component of evaporite deposits.
Evaporite: A sedimentary deposit formed when dissolved minerals precipitate as water evaporates. Evaporation concentrates dissolved sulfate ions until sulfate minerals can crystallize.
Plaster: A workable building material made by mixing a binder with water and applying it as a paste. Heating gypsum produces plaster, which hardens when mixed with water.
Sulfide mineral: A mineral whose composition includes sulfur bonded to one or more elements, commonly metals. Sulfides contain sulfur without the oxygen-rich sulfate anion and often form in different environments.
Crystal structure: The orderly, repeating arrangement of atoms, ions, or molecules within a crystalline solid. The sulfate group’s arrangement with other constituents distinguishes one mineral structure from another.
Anhydrite: An anhydrous calcium sulfate mineral with the formula CaSO₄. Its composition contrasts with gypsum’s: anhydrite contains no water in its crystal structure.
Mineral precipitation: The formation of a solid mineral from a solution when dissolved constituents become supersaturated. Sulfate minerals precipitate when solution chemistry favors their crystallization.
Portland cement: A hydraulic cement made primarily from clinker and ground additives, including gypsum. Gypsum is added to regulate the setting time of Portland cement.
Sulfite: The polyatomic anion SO₃²⁻, containing one sulfur atom and three oxygen atoms. Sulfite has one fewer oxygen atom than sulfate and defines a distinct chemical group.

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