gemstone
Ruby (Cabochon)
Corundum (Al2O3)
Hardness: 9 on the Mohs scale. Color: Vivid red to purplish-red (due to chromium trace elements). Luster: Vitreous to sub-adamantine. Crystal System: Trigonal. Cleavage: None, parting on basal pinacoid. Specific Gravity: 3.98-4.10.
- Hardness
- 9 on the Mohs scale
- Color
- Vivid red to purplish-red (due to chromium trace elements)
- Luster
- Vitreous to sub-adamantine
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Physical properties
Hardness: 9 on the Mohs scale. Color: Vivid red to purplish-red (due to chromium trace elements). Luster: Vitreous to sub-adamantine. Crystal System: Trigonal. Cleavage: None, parting on basal pinacoid. Specific Gravity: 3.98-4.10.
Formation & geological history
Formed in metamorphic environments such as marble and gneiss, or alluvial secondary deposits where they are eroded from parent rocks.
Uses & applications
High-end jewelry, watch bearings, and laser technology.
Geological facts
Ruby is one of the traditional cardinal gemstones. The color is caused by trace amounts of chromium replacing aluminum in the crystal lattice.
Field identification & locations
Identified by its extreme hardness, red color, and high density. Can be found in marble-hosted deposits globally.
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