Celestite
Chemical Formula	SrSO4
Species	Sulfates
Crystal System	Orthorhombic
Mohs Scale	3-3.5
Specific Gravity	3.95-3.97
Color	Colorless, white, pale blue, pink, pale green, pale brown, black
Streak	white
Luster	Vitreous, pearly on cleavages
Refractive Index	nα = 1.619 - 1.622 nβ = 1.622 - 1.624 nγ = 1.630 - 1.632
Diaphaneity	Transparent to translucent
Cleavage	Perfect on , good on , poor on
Fracture	Uneven
Crystal Habit：Tabular to pyramidal crystals, also fibrous, lamellar, earthy, massive granular