mineral
Corundum
Aluminum Oxide (Al2O3)
AI-generated identification · may be incorrectHardness of 9 on the Mohs scale, specific gravity around 4.0, hexagonal crystal system, and vitreous to adamantine luster. Colors vary widely including brown, gray, blue, and yellow due to trace impurities.
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Physical properties
Hardness of 9 on the Mohs scale, specific gravity around 4.0, hexagonal crystal system, and vitreous to adamantine luster. Colors vary widely including brown, gray, blue, and yellow due to trace impurities.
Formation & geological history
Forms in metamorphic rocks like marble and schist, as well as igneous rocks such as syenites and pegmatites through cooling and crystallization under high pressure and temperature.
Uses & applications
Used primarily as an industrial abrasive, in refractory materials, and as precious gemstones (ruby and sapphire) in jewelry.
Geological facts
Corundum is the second hardest natural mineral on Earth, surpassed only by diamond. Its name originates from the Tamil word kurundam.
Field identification & locations
Identified by its extreme hardness which can scratch quartz and its distinct barrel-shaped hexagonal crystals. Commonly found in alluvial deposits, East Africa, India, and Madagascar.
