Carnallite

carnallite

sylvite

polyhalite

kieserite

Images

Formula: KMgCl3.6H2O
Halide complex
Specific gravity: 1.602
Hardness: 2½
Streak: White
Colour: Yellow to white, reddish, seldom white, colourless or blue
Solubility: Soluble in water, deliquescent
Common impurities: Br,Rb,Cs,Tl,Fe
Environments

Evaporite deposits

Carnallite is thought to form in saline marine deposits by reaction of pre-existing saline minerals with fluids high in potash. Associated minerals include kieserite, sylvite, halite, polyhalite and bischofite (HOM)
Carnallite forms an epiaxial relationship with hematite, with hematite scales oriented with {0001} parallel to carnallite {001}, also parallel {110} or {100} (Mindat).

Localities

At the type locality, Stassfurt, Stassfurt Potash deposit, Saxony-Anhalt, Germany, carnallite occurs in upper layers of the saline deposits associated with sylvite, polyhalite, kieserite and halite (Mindat).

At Eddy county, New Mexico, USA, drill cores contained predominantly colourless halite, brick-red sylvite and blood-red carnallite, with lesser amounts of pink polyhalite, white kieserite, anhydrite, and red or grey clay (AM 31.486-494).

At McCarthy, No. 1 well, Grand county, Utah, USA, in drill cores halite is the most abundant mineral. It is colourless or grey, medium-grained, and with interIocking grains. Carnallite and sylvite are also abundant, and kieserite, anhydrite and clay are present in small quantities (AM 31.486-494).

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