mineral

Celestine (Celestite)

Strontium sulfate (SrSO4)

Hardness: 3.0 - 3.5 on the Mohs scale; Color: Pale blue, colorless, or white; Luster: Vitreous (glassy) to pearly; Crystal Structure: Orthorhombic; Cleavage: Perfect; Specific Gravity: 3.9 - 4.0 (noticeably heavy).

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

Identified March 30, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in sedimentary rocks such as limestones and dolomites, often occurring in geodes or as massive aggregates. It can also form in hydrothermal veins or evaporite deposits. Most major deposits date from the Mesozoic era.

Uses & applications

Primary source of Strontium, used in fireworks (to create red flames), signal flares, and television glass. In the collector market, it is highly valued for its aesthetic blue crystals and use in metaphysical practices.

Geological facts

The name 'Celestine' is derived from the Latin word 'caelestis,' meaning 'celestial' or 'heavenly' in reference to its characteristic sky-blue color. The largest celestine geode in the world, 'Crystal Cave,' is located in Ohio and measures 35 feet deep.

Field identification & locations

Identify in the field by its distinct pale blue color, high density compared to other light-colored minerals, and its tendency to form in geodes within limestone. Major sources include Madagascar, Sicily, and Lake Erie (USA/Canada). Collectors should be careful as it is brittle.