mineral

Blue Sapphire

Corundum (Al2O3 with trace Titanium/Iron)

Hardness: 9 on the Mohs scale; Color: Deep blue with internal flash; Luster: Vitreous to sub-adamantine; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (has parting); Specific Gravity: 3.95-4.03.

Hardness: 9 on the Mohs scale
Color: Deep blue with internal flash
Luster: Vitreous to sub-adamantine

Identified April 6, 2026More mineral →

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Physical properties

Formation & geological history

Formed under high heat and pressure in metamorphic or igneous environments, most commonly found in marble or basalt-hosted deposits. Geological age varies by source, frequently millions of years old.

Uses & applications

A highly valued gemstone for fine jewelry (rings, necklaces); also used in industrial applications such as scratch-resistant watch crystals and high-durability optics.

Geological facts

Sapphire is the birthstone for September and is the second hardest natural substance after diamond. The blue color is specifically caused by trace amounts of iron and titanium replacing aluminum in the crystal lattice.

Field identification & locations

Identify by its exceptional hardness (cannot be scratched by steel) and lack of cleavage. Common locations include Sri Lanka, Madagascar, Myanmar, and Australia. In the field, look for hexagonal prismatic crystals.

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