Cryolite
Chemical Formula	Na3AlF6
Species	Halides
Crystal System	Monoclinic
Mohs Scale	2
Specific Gravity	2.95-3.0.
Color	Colorless to white, also brownish, reddish and rarely black
Streak	White
Luster	Vitreous, Greasy, Pearly
Refractive Index	n = 1.339 - 1.339 n = 1.339 - 1.339 n = 1.340 - 1.340
Diaphaneity	Transparent, Translucent
Cleavage	None Observed
Fracture	Irregular/Uneven
Crystal Habit：Usually massive, coarsely granular. The rare crystals are equant and pseudocubic
Geological Setting：Late stage mineral in granitic pegmatites, vapor phase mineral in rhyolites.