mineral

Celestite Geode

Celestine (Strontium Sulfate, SrSO4)

Hardness: 3.0 to 3.5 on Mohs scale; Color: Pale blue to sky blue; Luster: Vitreous to pearly; Crystal Structure: Orthorhombic; Cleavage: Perfect; Specific Gravity: 3.9 to 4.0

Hardness: 3
Color: Pale blue to sky blue
Luster: Vitreous to pearly

Identified May 17, 2026More mineral →

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Physical properties

Hardness: 3.0 to 3.5 on Mohs scale; Color: Pale blue to sky blue; Luster: Vitreous to pearly; Crystal Structure: Orthorhombic; Cleavage: Perfect; Specific Gravity: 3.9 to 4.0

Formation & geological history

Formed primarily in sedimentary rocks such as limestone or sandstone as a precipitate from strontium-rich solutions. It commonly occurs in geodes or cavities where mineral-rich groundwater slowly cools over geological time. Significant deposits found in Madagascar are often Cretaceous in age.

Uses & applications

Used commercially as a source of strontium for pyrotechnics (red firework flames) and flares. In the mineral market, it is highly valued for ornamental purposes, metaphysical collecting, and jewelry in the form of faceted stones (though rare due to softness).

Geological facts

The largest known geode in the world, the Crystal Cave in Ohio, is a celestite geode measuring 35 feet deep. The name is derived from the Latin word 'caelestis' meaning 'heavenly' or 'celestial' due to its characteristic sky-blue hue.

Field identification & locations

Identified in the field by its distinct pale blue color, high specific gravity (feels heavy for its size), and orthorhombic crystal habit. Major sources include Madagascar, Sicily, and Lake Erie region in North America. Collectors should be careful not to leave it in direct sunlight as the blue color can fade.