Class : Halides
    Subclass : Chlorides
    Crystal system : Cubic
    Chemistry : KCl
    Rarity : Common

Sylvite is, like halite, a mineral of evaporite deposits. These deposits result from the evaporation of large areas of shallow enclosed seas, a common phenomenon over geological time. Systematically associated with halite, sylvite is however less abundant than the latter because of its extreme solubility and easily remobilized. Potash is a rock composed of alternating centimeter-thick beds of halite and sylvite. It was named in honor of the Dutch chemist François Sylvius de la Boë who composed the sal digestibus Sylvii in the 17^th century. Sylvius' digestive salts were used to treat various digestive disorders because of their alkaline properties, which could neutralize gastric acids and facilitate digestion. Sylvite generally occurs in fibrous or granular crystalline masses, of low hardness (2) and low density (2). Theoretically colorless, sylvite is in fact usually colored yellow, red (the most common color), gray, or bluish, due to the presence of metallic elements, especially iron, or impurities. Its crystals are cubic, cubo-octahedral or octahedral, more rarely tetrahedral. Sylvite is the main source of potassium and potassium compounds. This property gives it a place of choice in the chemical and food industry, particularly for the manufacture of fertilizers. Sylvite is also used as a catalyst for the production of synthetic rubber.

Main photo : Sylvite from U. S. Potash Co. Mine, New Mexico, USA © Rock Currier

Twinning is common on {111} but only on artificial crystals.

No fakes listed for this mineral species.