mineral

Celestite

Celestine (SrSO4)

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

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

Identified July 9, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed as a sedimentary evaporite mineral or through hydrothermal activity. Often found in geodes within limestone or dolostone, particularly from the Mesozoic era.

Uses & applications

Main source of strontium used in fireworks, tracer bullets, and glass manufacturing; also highly valued by mineral collectors and for metaphysical use.

Geological facts

The world's largest known geode is a celestite geode located in Ohio, USA, measuring 35 feet deep. Its name is derived from the Latin 'caelestis', meaning celestial, referring to its sky-blue color.

Field identification & locations

Identify by its distinct pale blue color, high density (heavy for its size), and lack of reaction to acid. Common in Madagascar, USA (Ohio, Michigan), and Poland.