mineral

Celestine

Celestine (Strontium Sulfate, SrSO4)

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

Hardness: 3-3

Identified June 24, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed primarily in sedimentary rocks such as limestones and dolomites via precipitation from strontium-rich groundwater or in evaporite deposits. Most famous deposits are from the Mesozoic or Cenozoic era.

Uses & applications

Primary source of Strontium used in fireworks (red flames), television glass, and magnets; also used as a gemstone for collectors and in holistic practices.

Geological facts

The name is derived from the Latin 'caelestis', meaning celestial, referring to its sky-blue color. The largest known geode in the world is a celestine geode located on South Bass Island in Ohio.

Field identification & locations

Identify by its distinct pale blue color, orthorhombic crystalline form, and notable heaviness compared to similar-looking minerals like quartz. Commonly found in Madagascar and the United States.