mineral

Blue Sapphire

Corundum (Al2O3) with traces of Iron and Titanium

Hardness: 9.0 on Mohs scale; Color: Ranges from pale to deep blue; Luster: Vitreous; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (has parting); Specific Gravity: 3.98 - 4.06

Hardness: 9
Color: Ranges from pale to deep blue
Luster: Vitreous

Identified March 26, 2026More mineral →

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Physical properties

Hardness: 9.0 on Mohs scale; Color: Ranges from pale to deep blue; Luster: Vitreous; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (has parting); Specific Gravity: 3.98 - 4.06

Formation & geological history

Formed in metamorphic or igneous rocks such as marble, basalt, or pegmatites; typically found in alluvial deposits or primary rock formations. Ages range from millions to over a billion years depending on the deposit (e.g., Sri Lanka or Madagascar).

Uses & applications

Primary use in high-end jewelry (gemstone), industrial abrasives, watch crystals, and high-durability windows (synthetic versions).

Geological facts

Sapphire is the birthstone for September and is the second hardest natural mineral after diamond. Famous specimens include the 'Star of India' and the 'Logan Sapphire.'

Field identification & locations

Identify in the field by its extreme hardness (cannot be scratched by quartz or steel) and high density. Commonly found in riverbeds (alluvial) in Sri Lanka, Myanmar, Thailand, and Montana, USA.

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