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Luster: Vitreous or adamantine
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Hardness: 9
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Cleavage/Fracture: Conchoidal
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Color: All colors, excludng blood-red or red with a purple tinge.
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Habit: Can be found as tapering prismatic, pyramidal, or tabular, often is striated. Star sapphire has rutile inclusions that form four, five or six-pointed stars.
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Environment of Origin: Sapphires are the non-red variety of corundum, which is formed in nepheline syenite pegmatites, in contact metamorphic rocks and metamorphic terrains that are aluminum-rich and silica-poor.
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