Celestine
ID: 7
Celestine
Chemical Formula
SrSO₄
Hardness (Mohs)
3–3.5
Crystal System
Orthorhombic
Streak
White
Luster
Vitreous to pearly
Diaphaneity
Transparent to translucent
Color
Pale blue, white, or gray
Cleavage
Perfect in one direction
Crystal Habit / Mode of Occurrence
Orthorhombic tabular or prismatic crystals, commonly found in sedimentary rocks and evaporite deposits
Density
~3.9–4.0 g/cm³
Fun Facts
Celestine is the primary source of strontium, used in fireworks and flares. Some specimens fluoresce under UV light.