mineral

Rough Ruby

Corundum (Al2O3 with Chromium impurities)

Hardness: 9 on Mohs scale; Color: Deep pink to blood-red; Luster: Adamantine to vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None (may show basal parting); Specific gravity: 3.97-4.05

Hardness: 9 on Mohs scale
Color: Deep pink to blood-red
Luster: Adamantine to vitreous

Identified March 25, 2026More mineral →

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Physical properties

Hardness: 9 on Mohs scale; Color: Deep pink to blood-red; Luster: Adamantine to vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None (may show basal parting); Specific gravity: 3.97-4.05

Formation & geological history

Formed in metamorphic rocks (schists or marbles) or igneous environments (syenites) where silicon is low. Often found in secondary alluvial deposits (river beds) after errosion from host rock.

Uses & applications

High-quality stones used in jewelry; lower grades used as industrial abrasives, in laser technology (synthetic rubies), and as watch bearings.

Geological facts

Ruby is the red variety of the mineral corundum; every other color of corundum is called sapphire. It is the birthstone for July and is often associated with vitality and passion.

Field identification & locations

Identify by its extreme hardness (will scratch almost any other mineral except diamond) and hexagonal crystal habit. Common locations include Myanmar (Burma), Sri Lanka, Thailand, and East Africa.

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