gemstone
Blue Topaz
Al2SiO4(F,OH)2
Hardness of 8 on the Mohs scale, vitreous luster, brilliant blue color often achieved through treatment, orthorhombic crystal system, perfect basal cleavage, specific gravity of 3.49-3.57.
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Physical properties
Hardness of 8 on the Mohs scale, vitreous luster, brilliant blue color often achieved through treatment, orthorhombic crystal system, perfect basal cleavage, specific gravity of 3.49-3.57.
Formation & geological history
Formed in igneous rocks such as pegmatites and granites, as well as in cavities and veinlets in rhyolite and metamorphic rocks like gneiss.
Uses & applications
Used primarily in fine jewelry, rings, necklaces, and as a collector's gemstone.
Geological facts
Natural blue topaz is extremely rare; most commercial blue topaz is colorless topaz treated with irradiation and heat to achieve its vibrant blue color.
Field identification & locations
Identified by its high hardness, vitreous luster, and crystal habits. Found worldwide including Brazil, Sri Lanka, Nigeria, and the US.
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