Celestite

By far the most common strontium mineral.

Name

Originally named fasriger schwerspath by Andreas Gotthelf Schütz in 1791. Renamed schwefelsaurer strontianite aus Pennsylvania by Martin Klaproth in 1797. Renamed by Abraham Gottlieb Werner in 1798 in German zoelestinfrom the Greek cœlestis for celestial, in allusion to the faint blue color of the original specimen. Renamed Schützit by Dietrich Ludwig Gustav Karsten in 1800. Although far superior celestine crystals were previously known from Sicily, they were thought to be barium-rich as the element strontium was not discovered until the late 1780s and not formally described until 1792.

Physical Properties

Lustre: Vitreous, Pearly
Transparency: Transparent, Translucent
Colour: Colourless, shades of light blue, white, reddish, greenish, brownish, greyish; colourless or lightly tinted in transmitted light
Streak: White
Hardness: 3 - 3½ on Mohs scale
Tenacity: Brittle
Cleavage: Perfect. On {001} perfect; on {210} good; on {010} poor. Also reported on {011}
Parting: Twin gliding and translation gliding
Fracture: Irregular/Uneven
Density: 3.96 - 3.98 g/cm3 (Measured) 3.98 g/cm3 (Calculated)

Chemical Properties

Formula: SrSO4
Elements listed: O, S, Sr

Crystallography

Crystal System: Orthorhombic
Class (H–M): mmm (2/m 2/m 2/m) - Dipyramidal
Space Group: Pnma
Morphology: Crystals commonly thin to thick tabular {001}, usually with large {210}; tabular {001} and elongated [100] yielding lath-like forms; or elongated [100] with equant cross section. Equant by development of {001}, {011}, {101} of otherwise, less common. Pyramidal {122}; elongated [010] or [001]; tabular {100}, {100} commonly striated [001]. Fibrous veinlets or nodules with parallel or radiated fiber structure; massive granular; lamellar, earthy, rare.
Twinning: Reported on {210}, {101}, and other planes (doubtful).