mineral
Blue Topaz
Aluminum silicate fluoride hydroxide (Al2SiO4(F, OH)2)
AI-generated identification · may be incorrectHardness: 8.0, Color: Light to vibrant blue (London, Swiss, or Sky), Luster: Vitreous (glassy), Crystal Structure: Orthorhombic, Cleavage: Perfect basal (one direction), Specific Gravity: 3.49–3.57
- Hardness
- 8
Identified More mineral →
Explore Blue Topaz in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 8.0, Color: Light to vibrant blue (London, Swiss, or Sky), Luster: Vitreous (glassy), Crystal Structure: Orthorhombic, Cleavage: Perfect basal (one direction), Specific Gravity: 3.49–3.57
Formation & geological history
Formed in acidic igneous rocks like granite and rhyolite, often in pegmatite veins or cavity fillings. Natural blue topaz is rare; most commercial specimens are colorless topaz treated with irradiation and heat.
Uses & applications
Primarily used as a gemstone in high-end and fashion jewelry (rings, pendants, earrings). Industrial use is limited due to heat sensitivity, though natural colorless topaz is sometimes a source of fluorine.
Geological facts
Topaz is the birthstone for November, though blue topaz is often used as an alternative for December. It is the state gemstone of Texas. Most blue topaz in the market is irradiated to achieve its deep color.
Field identification & locations
Identify by its hardness (scratches glass/quartz) and high refractive index. In the field, it is found in alluvial deposits or within granite pegmatites. Common locations include Brazil, Sri Lanka, and Russia.
