mineral

Ruby (Raw Corundum)

Corundum (Al2O3) with Chromium traces

Hardness: 9 on Mohs scale; Color: Red to deep purplish-red; Luster: Adamantine to vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: No true cleavage (displays parting); Specific gravity: 3.97-4.05

Hardness: 9 on Mohs scale
Color: Red to deep purplish-red
Luster: Adamantine to vitreous

Identified June 24, 2026More mineral →

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Physical properties

Formation & geological history

Formed in metamorphic rocks seperti schists, gneisses, and marbles through contact or regional metamorphism of aluminum-rich sediments. Also found in igneous rocks such as syenite.

Uses & applications

Used primarily in high-end jewelry as a gemstone, industrial abrasives due to hardness, and historic use in ruby lasers.

Geological facts

Ruby is the red variety of the mineral corundum; every other color is called sapphire. It is second only to diamonds in terms of natural mineral hardness.

Field identification & locations

Identify by its hexagonal barrel shape (prisms), extreme hardness, and purplish-red hue. Commonly found in Myanmar (Burma), Madagascar, Thailand, and Mozambique.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral