mineral

Blue Sapphire

Corundum (Al2O3 - Aluminum Oxide)

Hardness: 9 on the Mohs scale. Color: Cornflower blue to deep navy. Luster: Vitreous (glass-like). Crystal Structure: Trigonal. Cleavage: None. Specific Gravity: 3.98 - 4.06.

Hardness: 9 on the Mohs scale
Color: Cornflower blue to deep navy
Luster: Vitreous (glass-like)

Identified March 26, 2026More mineral →

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Physical properties

Hardness: 9 on the Mohs scale. Color: Cornflower blue to deep navy. Luster: Vitreous (glass-like). Crystal Structure: Trigonal. Cleavage: None. Specific Gravity: 3.98 - 4.06.

Formation & geological history

Formed through regional or contact metamorphism of aluminum-rich rocks or in igneous environments such as pegmatites and alkali basalts. Geological age varies from 20 million up to 1 billion years old.

Uses & applications

Predominantly used as a gemstone for jewelry (rings, necklaces); industrial-grade sapphire is used for watch crystals, electronics, and scratch-resistant optical components.

Geological facts

Sapphire is the second hardest natural mineral after diamond. Blue color is caused by trace amounts of iron and titanium within the aluminum oxide crystal lattice.

Field identification & locations

Identify in the field by its extreme hardness (cannot be scratched by steel) and lack of cleavage. Common locations include Sri Lanka, Madagascar, Burma (Myanmar), and Montana, USA.