Answer: fluor

AnswerCrossword Clue
FLUORElement 9, informally
FLUORCrystalline mineral
fluorcommon mineral, calcium fluoride, CaF2, occurring in green, blue, purple, yellow, or colorless crystals, usually in cubes: the principal source of fluorine, used also as a flux in metallurgy and for ornament
fluora mineral form of calcium fluoride, also FLUORITE