gemstone
Yellow Sapphire
Corundum (Al2O3)
Hardness of 9 on the Mohs scale, yellow to orange-yellow color, vitreous to adamantine luster, trigonal crystal system, no true cleavage, specific gravity of approximately 4.0
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Physical properties
Hardness of 9 on the Mohs scale, yellow to orange-yellow color, vitreous to adamantine luster, trigonal crystal system, no true cleavage, specific gravity of approximately 4.0
Formation & geological history
Formed in metamorphic or igneous rocks, particularly in aluminum-rich and silica-deficient environments such as marble, pegmatites, and alluvial placer deposits over millions of years
Uses & applications
Used primarily in fine jewelry, luxury watches, and industrial applications due to its extreme hardness
Geological facts
Sapphires are the same mineral species as rubies (corundum); any color of corundum other than red is classified as a sapphire
Field identification & locations
Identified by its high density, exceptional hardness capable of scratching most other minerals, and characteristic crystal habit or rounded alluvial pebble shape; commonly found in Sri Lanka, Madagascar, and Australia
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