mineral

Celestine (Celestite)

Strontium sulfate (SrSO4)

Hardness: 3–3.5 on Mohs scale; Color: Pale blue, colorless, or white; Luster: Vitreous (glassy) to pearly; Crystal structure: Orthorhombic; Specific Gravity: 3.9–4.0

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

Identified July 2, 2026More mineral →

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Physical properties

Hardness: 3–3.5 on Mohs scale; Color: Pale blue, colorless, or white; Luster: Vitreous (glassy) to pearly; Crystal structure: Orthorhombic; Specific Gravity: 3.9–4.0

Formation & geological history

Formed primarily in sedimentary rocks such as limestone or dolomite as a precipitate from strontium-rich fluids in cavities or geodes. Found globaly in deposits ranging from Paleozoic to modern eras.

Uses & applications

Primary source of strontium for fireworks (red flames) and flares; also used in glass manufacturing, metallurgy, and highly valued as a decorative collector's specimen.

Geological facts

The world's largest known geode is a Celestine geode located in Put-in-Bay, Ohio, measuring 35 feet (11 meters) in diameter. The name is derived from the Latin word 'caelestis', meaning celestial or heavenly, referring to its sky-blue color.

Field identification & locations

Identified in the field by its high density (heavy for its size), distinct light blue color, and fragile orthorhombic crystals. Commonly found in Madagascar and Ohio.