mineral

Celestine (or Celestite)

Strontium sulfate (SrSO4)

Hardness: 3-3.5 (Mohs scale); Color: Pale blue, colorless, white; Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Cleavage: Perfect; Specific gravity: 3.9-4.0

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

Identified April 20, 2026More mineral →

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Physical properties

Hardness: 3-3.5 (Mohs scale); Color: Pale blue, colorless, white; Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Cleavage: Perfect; Specific gravity: 3.9-4.0

Formation & geological history

Usually found in sedimentary rocks (dolostone, limestone) formed from hydrothermal veins or as geodes in evaporated seawater basins. Often associated with gypsum, anhydrite, and halite. Most specimens are from the Phanerozoic eon.

Uses & applications

Primary source of chemical strontium used in pyrotechnics (fireworks), ferrite magnets, and glass manufacture. It is highly valued as a decorative collector mineral.

Geological facts

The mineral's name is derived from the Latin word 'caelestis', meaning 'heavenly', referring to its characteristic soft blue color. The world's largest known geode is a Celestine geode located in Ohio, USA, measuring 30 feet in diameter.

Field identification & locations

Identify in the field by its distinct pale blue color, high density (heavy for its size), and lack of reactivity to acid. Commonly found in Madagascar, Sicily, and the Lake Erie region of the United States/Canada.