gemstone
Blue Topaz
Al2SiO4(F,OH)2
AI-generated identification · may be incorrectHardness of 8 on the Mohs scale, vitreous luster, and orthorhombic crystal system. Exhibits distinct basal cleavage and specific gravity around 3.4-3.6.
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Physical properties
Hardness of 8 on the Mohs scale, vitreous luster, and orthorhombic crystal system. Exhibits distinct basal cleavage and specific gravity around 3.4-3.6.
Formation & geological history
Forms in pegmatites, high-temperature quartz veins, and cavities in rhyolite and granite rocks. Often artificially treated via irradiation and heating from colorless topaz.
Uses & applications
Widely used in fine jewelry such as rings, necklaces, and earrings. Popular as a birthstone and affordable alternative to sapphire.
Geological facts
Natural deep blue topaz is extremely rare, so most commercial blue topaz is heat-treated and irradiated. It is the state gemstone of Texas.
Field identification & locations
Identified by high hardness, cold feel, and distinct specific gravity compared to glass imitations. Found globally including Brazil, Sri Lanka, and the US.
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