Mineral

Celestite (Celestine)

Celestine (Strontium Sulfate, SrSO4)

Hardness: 3 - 3.5 on Mohs scale; Color: Pale blue, colorless, white; Luster: Vitreous (glassy) to pearly; Crystal Structure: Orthorhombic; Cleavage: Perfect basal; Specific Gravity: 3.9 - 4.0 (relatively high due to strontium content).

Hardness: 3 - 3
Color: Pale blue, colorless, white
Luster: Vitreous (glassy) to pearly

Identified March 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed in sedimentary rocks (chiefly evaporites) as a direct precipitate from seawater, or as a secondary mineral in carbonate rocks and geodes through hydrothermal activity. Major deposits date from the Cretaceous period.

Uses & applications

Primary source of the element Strontium, used in fireworks (to create red flames), signal flares, and television glass. In specimen form, it is highly valued for crystal collecting and metaphysical practices.

Geological facts

Its name is derived from the Latin 'caelestis', meaning celestial or heavenly, due to its characteristic sky-blue color. The largest celestite geode in the world is 'Crystal Cave' in Ohio, measuring 35 feet across at its widest point.

Field identification & locations

Identify by its pale blue color, high density (heavy for its size), and low hardness (scratched by a copper penny). It is most commonly found in Madagascar, Sicily, and Ohio, USA. Collectors should handle with care as it is brittle and can fade in direct sunlight.

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