Celestite is a mineral consisting of strontium sulfate (SrSO4). 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.
Celestine derives its name from the Latin word caelestis meaning celestial, which in turn is derived from the Latin word caelum meaning sky or heaven.
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.

Celestite

Celestite