mineral

Raw ruby (likely corundum)

Corundum, Al₂O₃; red varieties are ruby

AI-generated identification · may be incorrect

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.

Identified August 28, 2026More mineral →

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Physical properties

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.