mineral

Blue Sapphire

Corundum (Al2O3) with traces of Iron and Titanium

Hardness: 9 on Mohs scale; Color: Intense blue ranging from cornflower to royal blue; Luster: Vitreous (glass-like); Crystal structure: Trigonal/Hexagonal; Cleavage: None (has parting); Specific gravity: 3.95-4.03

Hardness: 9 on Mohs scale
Color: Intense blue ranging from cornflower to royal blue
Luster: Vitreous (glass-like)

Identified June 13, 2026More mineral →

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Physical properties

Formation & geological history

Formed under high pressure and temperature in metamorphic rocks like marble or gneiss, or as a primary mineral in igneous rocks like basalt. Commercially viable deposits are often found in alluvial (riverbed) gravels. Most deposits range from 5 to 150 million years old.

Uses & applications

Primarily used as a gemstone in high-end jewelry (rings, earrings, necklaces). Also used industrially in its synthetic form for scratch-resistant watch crystals, optical components, and industrial bearings.

Geological facts

Sapphire is the birthstone for September and is the second hardest natural substance on Earth after diamond. The most famous sapphire is the Star of India, weighing 563 carats.

Field identification & locations

Identify by its high hardness (it can scratch glass and steel easily) and remarkable brilliance when cut. Natural specimens often show 'silk' inclusions of rutile under magnification. Major sources include Sri Lanka, Madagascar, Myanmar, and Montana (USA).

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Mineral/Rock

Banded Gneiss (River Rock/Pebble)

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Metamorphic Rock

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mineral