mineral

Celestite

Celestine (SrSO4)

Hardness: 3-3.5 on Mohs scale; Color: Pale blue, white, colorless, sometimes reddish or greenish; Luster: Vitreous to pearly; Crystal System: Orthorhombic; Cleavage: Perfect in one direction, good in another; Specific Gravity: 3.9-4.0

Hardness: 3-3
Color: Pale blue, white, colorless, sometimes reddish or greenish
Luster: Vitreous to pearly

Identified July 29, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in sedimentary environments, often in cavities of limestone, sandstone, and evaporite deposits from the precipitation of strontium-rich marine waters.

Uses & applications

Used as an ore for the element strontium, in fireworks and pyrotechnics (for bright red colors, though ironically), in ceramics, and heavily collected as a decorative mineral and crystal specimen.

Geological facts

Named from the Latin word 'caelestis' meaning celestial, referring to the delicate sky-blue color of many specimens. The world's largest known geode is a massive celestite geode located in Put-in-Bay, Ohio, measuring 35 feet across.

Field identification & locations

Can be identified by its characteristic soft blue color, high density (heavy for its size), and orthorhombic crystal habit. Commonly found in Madagascar, Spain, Italy, and the USA.