mineral

Celestite (Celestine)

Strontium Sulfate (SrSO4)

Mohs hardness 3 - 3.5; Color: pale blue, sky blue, colorless, white, or light gray; Luster: vitreous to pearly; Crystal structure: orthorhombic; Cleavage: perfect in one direction; Specific Gravity: ~3.96 - 4.0

Color: pale blue, sky blue, colorless, white, or light gray
Luster: vitreous to pearly

Identified July 22, 2026More mineral →

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Physical properties

Formation & geological history

Forms primarily in sedimentary rocks such as limestones, dolomites, and evaporite deposits through precipitating hydrothermal fluids or secondary alteration.

Uses & applications

Primary ore of strontium, which is used in fireworks for red flames, glass production, and refining sugar. Highly valued as display specimens and by gemstone collectors.

Geological facts

The world's largest known celestite geode is the Crystal Cave located on South Bass Island in Lake Erie, Ohio, measuring up to 35 feet (10.7 meters) across.

Field identification & locations

Identified by its delicate pale blue color, high specific gravity (feels heavy for its size), and tabular or prismatic crystal habit. Major deposits are found in Madagascar, the UK, Mexico, and the USA.