mineral

Raw Corundum (Sapphire/Ruby variant)

Aluminum oxide (Al2O3)

AI-generated identification · may be incorrect

Hardness: 9 on Mohs scale; Color: Grayish-purple to blue; Luster: Adamantine to vitreous; Crystal structure: Trigonal/Hexagonal barrel shapes; Specific gravity: 3.95-4.10

Hardness: 9 on Mohs scale
Color: Grayish-purple to blue
Luster: Adamantine to vitreous

Identified May 19, 2026More mineral →

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Physical properties

Hardness: 9 on Mohs scale; Color: Grayish-purple to blue; Luster: Adamantine to vitreous; Crystal structure: Trigonal/Hexagonal barrel shapes; Specific gravity: 3.95-4.10

Formation & geological history

Formed in silica-poor igneous rocks (syenites, pegmatites) or metamorphic rocks like mica schists and crystalline limestones. Crystallizes at high temperature and pressure.

Uses & applications

Industrial abrasives, watch bearings, and gemstones. Non-gem quality specimens like this are primarily for mineral collection or industrial use.

Geological facts

Corundum is the second hardest natural mineral after diamond. A variety called 'emery' is a mixture of corundum and other minerals used for sandpaper.

Field identification & locations

Identify by its extreme hardness (cannot be scratched by steel or quartz) and characteristic hexagonal barrel-shaped crystal habit. Often found in alluvial deposits due to high density.