25 Photos
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

Celestine or celestite (SrSO₄) is a mineral consisting of strontium sulfate. The mineral is named for its occasional delicate blue color. Celestine is the principal source of the element strontium, commonly used in fireworks and in various metal alloys.

Occurrence

Celestine occurs as crystals, and also in compact massive and fibrous forms. It is mostly found in sedimentary rocks, often associated with the minerals gypsum, anhydrite, and halite.

The mineral is found worldwide, usually in small quantities. Pale blue crystal specimens are found in Madagascar.

The bodies of the protozoan Acantharea are made of celestine, unlike those of other radiolarians which are made of silica.

In carbonate marine sediments, burial dissolution is a recognised mechanism of celestine precipitation

Geodes

Celestine crystals are found in some geodes. The world's largest known geode, a celestine geode 35 feet (10.7 m) in diameter at its widest point, is located near the village of Put-in-Bay, Ohio, on South Bass Island in Lake Erie. The geode has been converted into a viewing cave, Crystal Cave, with the crystals which once composed the floor of the geode removed. The geode has celestine crystals as wide as 18 inches (46 cm) across, estimated to weigh up to 300 pounds (135 kg) each.