gemstone
Blue Topaz
Aluminum Silicate Fluoride Hydroxide - Al2SiO4(F,OH)2
Hardness: 8.0 on Mohs scale; Color: Electric or Sky Blue (often treated); Luster: Vitreous; Crystal Structure: Orthorhombic; Cleavage: Perfect basal; Specific Gravity: 3.49-3.57
- Hardness
- 8
- Color
- Electric or Sky Blue (often treated)
- Luster
- Vitreous
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Physical properties
Hardness: 8.0 on Mohs scale; Color: Electric or Sky Blue (often treated); Luster: Vitreous; Crystal Structure: Orthorhombic; Cleavage: Perfect basal; Specific Gravity: 3.49-3.57
Formation & geological history
Formed in late stages of igneous rock cooling, typically in pegmatites, rhyolites, or hydrothermal veins. Natural blue is rare; most faceted specimens are irradiated colorless topaz.
Uses & applications
Primarily used in high-end and commercial jewelry (rings, pendants, earrings). Also valued by gemstone collectors and for metaphysical practices.
Geological facts
Topaz is the birthstone for November, though the blue variety is specifically associated with December. It is one of the hardest silicate minerals in nature.
Field identification & locations
Identify by its high hardness (scratches quartz), high density, and smooth basal cleavage. Commonly sourced from Brazil, Nigeria, and Sri Lanka.
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