Celestite

Physical Properties

Hardness: 3-3.5 on Mohs scale; Color: Pale blue, colorless, white; Luster: Vitreous (glassy), pearly on cleavages; Crystal Structure: Orthorhombic; Cleavage: Perfect; Specific Gravity: 3.9-4.0

Formation & Geological History

Formed in sedimentary rocks such as limestones and dolomites, often in cavities or as nodules. Can also occur in hydrothermal veins. Primarily formed through evaporation of saltwater or from the transformation of gypsum/anhydrite.

Uses & Applications

Primary source of strontium (used in fireworks, flares, and glass production). Highly valued as a collector's mineral and used in metaphysical or decorative displays.

Geological Facts

Its name is derived from the Latin word 'caelestis' meaning 'heavenly', referring to the light blue color. Large geodes are commonly found in Madagascar, some large enough for a person to stand inside.

Field Identification & Locations

Identify in the field by its distinctive pale blue color, high density (heavy for its size), and orthorhombic crystal shape. Commonly found in Madagascar, Ohio (USA), Poland, and Sicily.

Identified on: 4/23/2026

Mode: Standard