mineral

Rough Ruby

Corundum (Al2O3 with Chromium impurities)

Hardness: 9 on Mohs scale; Color: Pinkish-red to deep red; Luster: Adamantine to vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None (has parting)

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

Identified June 25, 2026More mineral →

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Physical properties

Hardness: 9 on Mohs scale; Color: Pinkish-red to deep red; Luster: Adamantine to vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None (has parting)

Formation & geological history

Formed in metamorphic rocks seperti marble or schists, and sometimes in igneous rocks like basalt. It occurs through high-pressure and high-temperature regional metamorphism of aluminum-rich rocks.

Uses & applications

Used primarily in high-end jewelry as a gemstone, and in industrial applications such as lasers, precision instruments, and abrasives due to its extreme hardness.

Geological facts

Ruby is simply a red variety of the mineral corundum; every other color of corundum is called sapphire. It is one of the four traditional 'precious' stones.

Field identification & locations

Identify in the field by its distinct hexagonal crystal habit, exceptional hardness (will scratch almost any other mineral), and red glow under UV light (fluorescence). Commonly found in Myanmar, Thailand, and East Africa.

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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