Kainite

minerals

boracite

szaibelyite

Formula: KMg(SO4)Cl.3H2O
Hydrated sulphate containing halogen
Specific gravity: 2.15
Hardness: 2½ to 3
Streak: White
Colour: Colourless; yellow, brownish, greyish-green, red, violet, blue; colourless in transmitted light
Environments

Evaporite deposits
Metamorphic environments

Kainite is a secondary mineral formed only in marine evaporite potash deposits, often as a result of subsequent metamorphism, associated with sylvite, halite, carnallite, kieserite, polyhalite, langbeinite and picromerite (HOM, Dana).

Localities

The type locality, Leopoldshall, Stassfurt Potash deposit, Saxony-Anhalt, Germany, is a potash deposit of oceanic origin (Mindat).

At the Carlsbad Potash Mining District, Eddy county, New Mexico, USA, kainite occurs in potash deposits associated with sylvite and langbeinite (Dana).

Alteration

Kainite is decomposed by water into epsomite and sylvite (Mindat).
KMg(SO4)Cl.3H2O + 4H2O → Mg(SO4).7H2O + KCl

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