Carnallite is an evaporite mineral, a hydrated potassium magnesium chloride with formula KMgCl₃·6(H₂O). It is variably colored yellow to white, reddish, and sometimes colorless or blue. It is usually massive to fibrous with rare pseudohexagonal orthorhombic crystals. The mineral is deliquescent (absorbs moisture from the surrounding air) and specimens must be stored in an airtight container.