mineral

Blue Topaz

Topaz [Al2SiO4(F,OH)2]

Hardness: 8 on Mohs scale; Color: Pale to deep blue (often heat-treated); Luster: Vitreous; Crystal Structure: Orthorhombic; Cleavage: Perfect basal; Specific Gravity: 3.49–3.57.

Hardness: 8 on Mohs scale
Color: Pale to deep blue (often heat-treated)
Luster: Vitreous

Identified March 13, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 8 on Mohs scale; Color: Pale to deep blue (often heat-treated); Luster: Vitreous; Crystal Structure: Orthorhombic; Cleavage: Perfect basal; Specific Gravity: 3.49–3.57.

Formation & geological history

Formed in igneous environments, particularly in granite pegmatites and rhyolite, as well as in alluvial deposits. They occur when fluorine-bearing vapors are released during the final stages of magma crystallization.

Uses & applications

Primarily used in the jewelry industry as a gemstone for rings, necklaces, and earrings. In industrial applications, it is sometimes used for its hardness, though synthetic versions are more common.

Geological facts

Natural blue topaz is exceptionally rare; most specimens on the market are colorless or brown topaz that has been irradiated and heat-treated to achieve the 'London Blue' or 'Swiss Blue' shades.

Field identification & locations

Identify by its high hardness (it can scratch glass and quartz) and its high density. It is commonly found in Brazil, Sri Lanka, Russia, and Nigeria. For collectors, look for clarity and intensity of color.