mineral

Blue Topaz

Aluminum silicate fluoride hydroxide (Al2SiO4(F,OH)2)

AI-generated identification · may be incorrect

Hardness: 8.0 on the Mohs scale; Color: Sky blue to electric blue; Luster: Vitreous (glass-like); Crystal structure: Orthorhombic; Cleavage: Perfect basal; Specific gravity: 3.49–3.57.

Hardness: 8
Color: Sky blue to electric blue
Luster: Vitreous (glass-like)

Identified May 31, 2026More mineral →

Explore Blue Topaz in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 8.0 on the Mohs scale; Color: Sky blue to electric blue; Luster: Vitreous (glass-like); Crystal structure: Orthorhombic; Cleavage: Perfect basal; Specific gravity: 3.49–3.57.

Formation & geological history

Formed in igneous rocks like pegmatites and rhyolites during the late stages of magmatic crystallization, often from fluorine-bearing vapors. Commonly found in alluvial deposits. Geological age varies significantly by deposit.

Uses & applications

Primarily used in jewelry for pendants, rings, and earrings. Also used as a birthstone and by collectors as faceted specimens.

Geological facts

Natural blue topaz is rare; most blue topaz on the market is clear topaz that has been irradiated and heat-treated to achieve the blue color. The 'Swiss Blue' and 'London Blue' are famous trade names for these colors.

Field identification & locations

Identify by its high hardness (it can scratch glass and quartz) and its high density. It has a distinctive slippery feel. Found commonly in Brazil, USA (pikes peak), and Sri Lanka.