Mineral, KMgCl3.6H2O; sp. gr. 1.6; hardness 1–2; orthorhombic; normally white, occasionally yellowish and reddish; greasy lustre; massive and granular, the pseudo-hexagonal crystals being rare; no cleavage; occurs in evaporite deposits and is soluble in water; bitter taste. It is used as a fertilizer, and is named after the 19th-century mining engineer R. V. Carnall.