mineral

Ruby (Rough/Raw)

Corundum (Al2O3:Cr)

Hardness: 9 on the Mohs scale; Color: Pinkish-red to deep blood-red; Luster: Adamantine to vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None (has parting); Specific Gravity: 3.97-4.05

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

Identified April 14, 2026More mineral →

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Physical properties

Hardness: 9 on the Mohs scale; Color: Pinkish-red to deep blood-red; Luster: Adamantine to vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None (has parting); Specific Gravity: 3.97-4.05

Formation & geological history

Formed in high-pressure metamorphic environments, often found in marble host rocks or as water-worn pebbles in alluvial deposits. They date back hundreds of millions of years in various tectonic settings.

Uses & applications

High-quality specimens are used in fine jewelry. Lower quality or synthetic rubies are used in industrial applications such as lasers, precision tools, and watch bearings.

Geological facts

Ruby is the variety of corundum colored red by chromium; all other colors are called sapphire. It is the birthstone for July and symbolizes passion and protection.

Field identification & locations

Identify by its extreme hardness (will scratch glass and quartz) and its distinctive hexagonal crystal habit or red color. Commonly found in Myanmar (Burma), Madagascar, and Mozambique.