mineral
Ruby (Raw Corundum)
Al2O3 (Aluminum Oxide)
Hardness: 9 on the Mohs scale. Color: Purplish-red to pinkish-red. Luster: Vitreous to sub-adamantine. Crystal Structure: Hexagonal (Trigonal prisms/plates). Cleavage: None (has rhombohedral parting).
- Hardness
- 9 on the Mohs scale
- Color
- Purplish-red to pinkish-red
- Luster
- Vitreous to sub-adamantine
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Physical properties
Hardness: 9 on the Mohs scale. Color: Purplish-red to pinkish-red. Luster: Vitreous to sub-adamantine. Crystal Structure: Hexagonal (Trigonal prisms/plates). Cleavage: None (has rhombohedral parting).
Formation & geological history
Formed in aluminum-rich metamorphic rocks like marble or schist, and igneous rocks like syenite. Often found in secondary alluvial deposits (river beds).
Uses & applications
High-value gemstone for jewelry, industrial abrasives, and laser technology (synthetic rubies).
Geological facts
Ruby is the red variety of the mineral corundum; every other color of corundum is called sapphire. It is the second hardest natural mineral known.
Field identification & locations
Identify by its distinct hexagonal crystal shape, high density, and extreme hardness (will scratch almost any other mineral). Often found in Mysore, India or Myanmar.
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Mineral/Rock