A hydrous chloride of potassium and magnesium, sometimes found associated with deposits of rock salt.

a white or reddish mineral consisting of hydrous chlorides of potassium and magnesium; used as a fertilizer and as a source of potassium and magnesium

Carnallite is an evaporite mineral, a hydrated potassium magnesium chloride with formula: KMgCl3·6(H2O). It is variably colored yellow to white, reddish, to rarely colorless and blue. It is usually massive to fibrous with rare pseudohexagonal orthorhombic crystals.