mineral

Ruby

Corundum (Al2O3 with Chromium impurities)

Hardness: 9 on Mohs scale; Color: Pinkish-red to pigeon-blood red; Luster: Vitreous to sub-adamantine; Crystal structure: Trigonal/Hexagonal; Cleavage: None (has parting); Specific Gravity: 3.97-4.05

Hardness: 9 on Mohs scale
Color: Pinkish-red to pigeon-blood red
Luster: Vitreous to sub-adamantine

Identified April 29, 2026More mineral →

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Physical properties

Hardness: 9 on Mohs scale; Color: Pinkish-red to pigeon-blood red; Luster: Vitreous to sub-adamantine; Crystal structure: Trigonal/Hexagonal; Cleavage: None (has parting); Specific Gravity: 3.97-4.05

Formation & geological history

Formed in metamorphic rocks (schist or marble) or igneous rocks (basalt). Created under intense heat and pressure deep within the crust. Often found as water-worn pebbles in alluvial deposits.

Uses & applications

Primarily used in high-end jewelry as a precious gemstone. Historically used in the first working lasers (Ruby lasers) and as pivot bearings in mechanical watches.

Geological facts

Ruby is the red variety of the mineral corundum; every other color is called sapphire. The presence of chromium gives it both its red color and its fluorescent glow.

Field identification & locations

Identify by its extreme hardness (cannot be scratched by steel or quartz) and its distinctive pink-red hue. Commonly found in Myanmar (Burma), Thailand, Mozambique, and Sri Lanka.