carnallite

noun Mineralogy.

1. a white hydrous chloride of potassium and magnesium, KMgCl3⋅6H2O, used chiefly as a source of potassium and magnesium.

noun

1. a white or sometimes coloured mineral consisting of a hydrated chloride of potassium and magnesium in orthorhombic crystalline form: a source of potassium and also used as a fertilizer. Formula: KCl.MgCl 2 .6H 2 O