Answer: sylvines

AnswerCrossword Clue
sylvinescommon mineral, potassium chloride, KCl, colorless to milky-white or red, occurring in crystals, usually cubes, and masses with cubic cleavage, bitter in taste: the most important source of potassium
sylvinesSYLVINE, an ore of potassium, also SYLVITE, SYLVIN