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 no 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 no true cleavage.
Formation & geological history
Forms within metamorphic or igneous rocks, particularly aluminum-rich and silica-poor environments like marble and alkali basalts, over millions of years.
Uses & applications
Widely used in high-end jewelry, watch crystal fabrication, and industrial abrasive or optical applications.
Geological facts
Sapphire is the second-hardest natural mineral after diamond, and trace amounts of iron and titanium create its classic blue color.
Field identification & locations
Identify by its extreme hardness, heavy feel, and hexagonal crystal barrel shape when raw; commonly found in alluvial gravel deposits worldwide.
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