mineral
Ruby
Corundum (Al2O3 with Chromium trace elements)
AI-generated identification · may be incorrectHardness: 9 on Mohs scale; Color: Red (ranging from orangey-red to purplish-red); Luster: Vitreous to sub-adamantine; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (has parting); Specific Gravity: 3.97–4.05
- Hardness
- 9 on Mohs scale
- Color
- Red (ranging from orangey-red to purplish-red)
- Luster
- Vitreous to sub-adamantine
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Physical properties
Hardness: 9 on Mohs scale; Color: Red (ranging from orangey-red to purplish-red); Luster: Vitreous to sub-adamantine; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (has parting); Specific Gravity: 3.97–4.05
Formation & geological history
Formed through contact or regional metamorphism of aluminum-rich rocks and marbles. Most famous deposits are found in marble-hosted environments like the Mogok Valley in Myanmar (Burma), as well as in basalt-hosted or alluvial deposits.
Uses & applications
Primarily used as a high-value gemstone in fine jewelry. Industrial-grade synthetic rubies are used in lasers, watch bearings (jeweled movements), and high-pressure scientific equipment.
Geological facts
The red color is caused specifically by the presence of chromium. Without chromium, corundum is known as sapphire. The most valuable color is a deep, vivid red known as 'pigeon's blood'.
Field identification & locations
Identify by its extreme hardness (9), hexagonal crystal habit, and distinct pleochroism. Found in places like Myanmar, Thailand, Sri Lanka, and Madagascar. Collectors look for fluorescence under UV light, which many rubies exhibit due to chromium.
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