mineral

Blue Sapphire

Corundum (Al2O3)

Hardness: 9 on Mohs scale. Color: Deep blue (due to iron and titanium). Luster: Vitreous to Adamantine. Crystal Structure: Hexagonal (trigonal). Cleavage: None. Specific Gravity: 3.95-4.03.

Hardness: 9 on Mohs scale
Color: Deep blue (due to iron and titanium)
Luster: Vitreous to Adamantine

Identified May 2, 2026More mineral →

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Physical properties

Hardness: 9 on Mohs scale. Color: Deep blue (due to iron and titanium). Luster: Vitreous to Adamantine. Crystal Structure: Hexagonal (trigonal). Cleavage: None. Specific Gravity: 3.95-4.03.

Formation & geological history

Formed in aluminum-rich igneous and metamorphic rocks (schists and gneisses) under high pressure and temperature. Found globally in alluvial deposits and primary rock formations.

Uses & applications

Primary use is in high-end jewelry and as a gemstone. Industrial uses include watch crystals, high-durability windows, and abrasive compounds due to its extreme hardness.

Geological facts

Sapphire is the birthstone for September and symbolizes wisdom and royalty. The most famous is the Star of India, weighing 563 carats. Red corundum is classified as Ruby, while all other colors are Sapphires.

Field identification & locations

Identify by its hardness (scratches glass/quartz) and heavy weight for its size. Natural field identification often occurs in gravel beds (placers) near metamorphic terrain. Often found in Sri Lanka, Madagascar, and Kashmir.