POTASH MINERAL SCIENCE

In opacity, sylvite (potassium chloride, KCl), carnallite (hydrous potassium magnesium chloride, KMgCl3·6H2O), and langbeinite (potassium magnesium sulfate, K2Mg2(SO4)3) are transparent to translucent. When nearly pure they are colorless, but impurities often impart a range of colors. The common yellow-orange and reddish-brown hues are caused by inclusions of particulate hematite.