Kainite
Kainite ( or ) (KMg(SO)Cl·3HO) is an evaporite mineral in the class of "Sulfates (selenates, etc.) with additional anions, with HO" according to the Nickel–Strunz classification. It is a hydrated potassium-magnesium sulfate-chloride, naturally occurring in irregular granular masses or as crystalline coatings in cavities or fissures. This mineral is dull and soft, and is colored white, yellowish, grey, reddish, or blue to violet. Its name is derived from Greek καινος [kainos] ("(hitherto) unknown"), as it was the first mineral discovered that contained both sulfate and chloride as anions. Kainite forms monoclinic crystals. Properties. Kainite is of bitter taste  and soluble in water. On recrystallization picromerite is deposited from the solution. Genesis and occurrence. Kainite was discovered in the Stassfurt salt mines in today's Saxony-Anhalt, Germany in 1865 by the mine official Schöne and was first described by Carl Friedrich Jacob Zincken. Kainite is a typical secondary mineral that forms through metamorphosis in marine deposits of potassium carbonate, and is also occasionally formed through resublimation from volcanic vapours. It is often accompanied by anhydrite, carnallite, halite, and kieserite. Kainite is only found in comparatively few places, among them in salt mines in central and northern Germany, Bad  Ischl (Austria), on Pasquasia in Sicily, in Whitby (UK), and in the Carlsbad Potash District in New Mexico, in volcanic deposits in Kamchatka and in Iceland, and in salt lakes in western China. It has also been identified in Gusev Crater on Mars. Uses. Kainite is used as a source of potassium and magnesium compounds, as a fertilizer, and as gritting salt.