mineral

Rough Sapphire (possibly Yellow/Green Corundum)

Corundum (Al2O3)

AI-generated identification · may be incorrect

Hexagonal crystal system, hardness 9 on Mohs scale, vitreous to adamantine luster, no cleavage, specific gravity 3.98-4.06, pale yellow-green color with internal fractures.

Identified July 10, 2026More mineral →

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Physical properties

Hexagonal crystal system, hardness 9 on Mohs scale, vitreous to adamantine luster, no cleavage, specific gravity 3.98-4.06, pale yellow-green color with internal fractures.

Formation & geological history

Formed in aluminum-rich metamorphic rocks (schists, gneisses) or igneous rocks like syenite. Often found as water-worn pebbles in alluvial deposits (gem gravels).

Uses & applications

Abrasives (industrial grade) or faceted as gemstones for jewelry (gem grade). High-quality stones are valuable to collectors.

Geological facts

Corundum is the second hardest natural mineral after diamond. When it is red, it is called ruby; every other color is called sapphire. Common sapphire often appears in pale, muddy tones like this specimen.

Field identification & locations

Identified by its extreme hardness (cannot be scratched by quartz or steel) and high density. Commonly found in Sri Lanka, Madagascar, and East Africa in riverbeds.