mineral

Celestite (Celestine)

Celestine (SrSO4)

Hardness: 3 - 3.5 on Mohs scale; Color: Pale blue, colorless, white; Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Cleavage: Perfect; Specific gravity: 3.9 - 4.0.

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

Identified June 15, 2026More mineral →

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Physical properties

Hardness: 3 - 3.5 on Mohs scale; Color: Pale blue, colorless, white; 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, often found in geodes where it precipitates from strontium-rich groundwater. It can also form in hydrothermal veins.

Uses & applications

Major source of the element strontium, which is used in fireworks (red flames), flares, television glass (cathode ray tubes), and ferrite magnets. Used in jewelry as a collector's gemstone and as a decorative display mineral.

Geological facts

The 'Crystal Cave' in Put-in-Bay, Ohio, is the world's largest known celestite geode. Its name is derived from the Latin word 'caelestis' meaning 'heavenly,' referring to its typical sky-blue color.

Field identification & locations

Identified in the field by its high density (heavy for its size), perfect cleavage, and sky-blue color. It can be found globally with famous high-quality deposits in Madagascar, Sicily, and Lake Erie, USA.