mineral

Sapphire (Raw/Rough)

Corundum (Al2O3)

Hardness: 9 on Mohs scale; Color: Blue (traces of iron and titanium); Luster: Adamantine to vitreous; Crystal structure: Hexagonal; Cleavage: None (rhombohedral parting); Specific Gravity: 3.95–4.03

Hardness: 9 on Mohs scale
Color: Blue (traces of iron and titanium)
Luster: Adamantine to vitreous

Identified April 3, 2026More mineral →

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Physical properties

Formation & geological history

Formed deep in the Earth's crust or mantle under high pressure and temperature. Found in igneous rocks like basalt and syenite, or metamorphic rocks like schist and marble. Often concentrated in alluvial deposits (river beds).

Uses & applications

Used primarily in jewelry as a precious gemstone. Industrial applications include infrared optical components, high-durability windows, and watch crystals due to extreme hardness.

Geological facts

Sapphire is the birthstone for September. Every color of the mineral corundum is called sapphire, except for red, which is classified as ruby.

Field identification & locations

Identify in the field by its extreme hardness (will scratch glass and most other minerals) and its high density (feels heavy for its size). Look for hexagonal crystal shapes in rough specimens.