mineral
Ruby (varieties of Corundum)
Aluminum oxide (Al2O3) with Chromium traces
AI-generated identification · may be incorrectHardness: 9.0 Mohs scale; Color: Deep red to pink-red; Luster: Vitreous; Crystal Structure: Trigonal (hexagonal); Cleavage: None (has parting); Specific gravity: 3.97-4.05
- Hardness
- 9
- Color
- Deep red to pink-red
- Luster
- Vitreous
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Physical properties
Hardness: 9.0 Mohs scale; Color: Deep red to pink-red; Luster: Vitreous; Crystal Structure: Trigonal (hexagonal); Cleavage: None (has parting); Specific gravity: 3.97-4.05
Formation & geological history
Formed in metamorphic rocks (schist or marble) and igneous rocks (basalt) via contact metamorphism; found in ancient gravel deposits (alluvial)
Uses & applications
Highly valued as a precious gemstone in jewelry, industrial lasers, and historically as bearings in mechanical watches
Geological facts
The red color comes from chromium; without it, the stone is a blue sapphire. Famous specimens include the Liberty Bell Ruby and the Sunrise Ruby.
Field identification & locations
Identify by intense red color, high hardness (scratches glass/most minerals), and absence of cleavage; found in Myanmar, Sri Lanka, and Thailand.
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Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous