mineral

Celestite (Celectine)

Strontium sulfate (SrSO4)

Hardness: 3.0 - 3.5 on Mohs scale; Color: typically pale blue but can be colorless/white; Luster: vitreous to pearly; Crystal Structure: Orthorhombic; Cleavage: perfect in one direction; Specific Gravity: 3.9 - 4.0 (unusually heavy for its appearance)

Hardness: 3
Color: typically pale blue but can be colorless/white
Luster: vitreous to pearly

Identified March 21, 2026More mineral →

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Physical properties

Formation & geological history

Formed through hydrothermal processes, typically in sedimentary rocks like limestone or dolomite, often occurring as geodes or within evaporate deposits. Can be found in rocks from the Paleozoic and Mesozoic eras.

Uses & applications

Primary source for strontium, used in fireworks and flares for red color, ceramic glazes, glass manufacturing, and highly valued by mineral collectors for its delicate blue crystals.

Geological facts

The world's largest known geode is a celestite geode found in Ohio, measuring 35 feet at its widest point. The name comes from the Latin word 'caelestis' meaning celestial or heavenly, referring to its blue color.

Field identification & locations

Identify by its distinct pale blue tint, high density (feels heavy for its size), and glassy luster. Common locations include Madagascar (best quality), Ohio and Michigan (USA), Morocco, and Sicily. Collectors should handle gently due to its high fragility.