mineral
Sapphire
Corundum (Al2O3)
Hardness: 9 on Mohs scale, Color: typically blue but can be pink, yellow, green, white, or multi-colored, Luster: vitreous to adamantine, Crystal structure: trigonal, Cleavage: none, Specific gravity: 3.95-4.10
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Physical properties
Hardness: 9 on Mohs scale, Color: typically blue but can be pink, yellow, green, white, or multi-colored, Luster: vitreous to adamantine, Crystal structure: trigonal, Cleavage: none, Specific gravity: 3.95-4.10
Formation & geological history
Forms in igneous rocks like syenites and pegmatites, and in metamorphic rocks like marble
Uses & applications
Primarily used as a gemstone in jewelry, also used industrially for abrasives and in high-durability windows and scientific instruments
Geological facts
Sapphire is the birthstone for September and is one of the four precious stones, along with diamond, ruby, and emerald
Field identification & locations
Can be identified by its high hardness (only diamond is harder) and high specific gravity. Found in countries like Sri Lanka, Madagascar, Australia, and the USA (Montana). Collectors look for vibrant, evenly distributed color and good clarity
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