gemstone
Sapphire
Corundum (Al2O3)
AI-generated identification · may be incorrectMohs hardness of 9; deep blue color; vitreous to adamantine luster; trigonal crystal system; specific gravity around 4.0.
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Physical properties
Mohs hardness of 9; deep blue color; vitreous to adamantine luster; trigonal crystal system; specific gravity around 4.0.
Formation & geological history
Forms in aluminum-rich metamorphic or igneous rocks like pegmatites and marbles under high pressure and temperature.
Uses & applications
Used extensively in fine jewelry, watch crystals, and industrial abrasives.
Geological facts
It is the second hardest natural mineral on Earth, surpassed only by diamond.
Field identification & locations
Identify by its extreme hardness, crystal habit, and characteristic blue hue; found in alluvial deposits worldwide.
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