mineral

Rough Topaz

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

Hardness: 8.0 on Mohs scale; Color: Yellow, honey-brown, or colorless (as shown); Luster: Vitreous; Crystal structure: Orthorhombic; Cleavage: Perfect basal; Specific gravity: 3.4 to 3.6

Hardness: 8
Color: Yellow, honey-brown, or colorless (as shown)
Luster: Vitreous

Identified March 14, 2026More mineral →

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Physical properties

Hardness: 8.0 on Mohs scale; Color: Yellow, honey-brown, or colorless (as shown); Luster: Vitreous; Crystal structure: Orthorhombic; Cleavage: Perfect basal; Specific gravity: 3.4 to 3.6

Formation & geological history

Formed through fluorine-bearing vapors given off during the last stages of the crystallization of igneous rocks. It is most commonly found in cavities of granitic pegmatites, rhyolites, and secondary alluvial deposits.

Uses & applications

Primary use is in jewelry as a gemstone. It is also a minor industrial source of fluorine and is highly sought after by mineral collectors for its crystal clarity and diverse colors.

Geological facts

Topaz is one of the hardest of all naturally occurring minerals. Historically, all yellow gems were called topaz; however, true topaz is chemically distinct and much harder than citrine (quartz) which is often sold as 'topaz'.

Field identification & locations

Field identification is based on its high hardness (it will scratch quartz), distinct heavy feel (high specific gravity), and its tendency to break along a perfectly flat plane (basal cleavage). Found in regions like Brazil, Nigeria, Sri Lanka, and Utah (USA).

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