gemstone
Sapphire
Corundum (Al2O3)
AI-generated identification · may be incorrectHardness of 9 on the Mohs scale, typically blue, vitreous to adamantine luster, trigonal crystal system, and distinct parting rather than true cleavage.
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Physical properties
Hardness of 9 on the Mohs scale, typically blue, vitreous to adamantine luster, trigonal crystal system, and distinct parting rather than true cleavage.
Formation & geological history
Forms in aluminum-rich metamorphic or igneous environments, such as marble or alkali basalts, over millions of years.
Uses & applications
Extensively used in fine jewelry, watch crystals, and industrial abrasive or optical components.
Geological facts
Sapphire is the second hardest natural mineral after diamond and includes all gem-quality varieties of corundum except red (which is ruby).
Field identification & locations
Identify by its extreme hardness, high specific gravity, and hexagonal crystal barrel shape; commonly found in alluvial gravel deposits.
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