mineral
Raw ruby (likely corundum)
Corundum, Al₂O₃; red varieties are ruby
AI-generated identification · may be incorrectOpaque to translucent purplish-red, with vitreous to greasy luster and irregular fractures; hardness 9 Mohs, trigonal crystal structure, no cleavage, and specific gravity about 4.0. The rough form may contain mica or other matrix minerals.
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Physical properties
Opaque to translucent purplish-red, with vitreous to greasy luster and irregular fractures; hardness 9 Mohs, trigonal crystal structure, no cleavage, and specific gravity about 4.0. The rough form may contain mica or other matrix minerals.
Formation & geological history
Forms mainly in metamorphic rocks such as marble and mica schist, or in basaltic/alluvial deposits; ruby-bearing rocks commonly formed during ancient mountain-building events, often hundreds of millions to over a billion years ago.
Uses & applications
Gem-quality material is cut into jewelry stones, while opaque specimens are collected or used as mineralogical references and occasionally as abrasive corundum.
Geological facts
The photograph is consistent with ruby-bearing corundum, but color alone cannot distinguish ruby from dyed material, garnet, spinel, or glass. Chromium commonly produces ruby’s red color.
Field identification & locations
Check for exceptional hardness, strong vitreous luster, and density; ruby commonly occurs with white calcite, mica, or dark host rock. Important localities include Myanmar, Mozambique, Sri Lanka, Afghanistan, Vietnam, and Tanzania.
