Mineral

Celestite (Celestine)

Strontium sulfate (SrSO4)

Hardness: 3-3.5 on Mohs scale; Color: Pale blue, colorless, or white (rarely pink/green); Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Cleavage: Perfect; Specific gravity: 3.9-4.0

Hardness: 3-3
Color: Pale blue, colorless, or white (rarely pink/green)
Luster: Vitreous to pearly

Identified March 15, 2026More mineral →

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Physical properties

Hardness: 3-3.5 on Mohs scale; Color: Pale blue, colorless, or white (rarely pink/green); Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Cleavage: Perfect; Specific gravity: 3.9-4.0

Formation & geological history

Formed as a sedimentary evaporite mineral, or through hydrothermal action in veins and cavities. Often found in geodes within limestone or dolostone. Major deposits date from the Mesozoic Era.

Uses & applications

Primary source of the element strontium, used in fireworks (red flames), ceramics, and glass manufacturing. Highly popular as a collector's mineral and in metaphysical practices.

Geological facts

Its name is derived from the Latin word 'caelestis,' meaning 'celestial' or 'heavenly,' due to its characteristic sky-blue color. The largest celestite geode found is 35 feet across at its widest point, located in Ohio, USA.

Field identification & locations

Identify by its pale blue hue, high density (feels heavy for its size), and lack of reaction to acid. Most commercial specimens are sourced from Madagascar. Note: Prolonged exposure to direct sunlight can cause the blue color to fade.