Properties
| Category | Nesosilicate |
|---|---|
| Formula | Al2SiO4(F, OH)2 |
| Crystal system | Orthorhombic |
| Color | Colorless (if impurities are absent), white, blue, brown, orange, gray, yellow, yellowish brown, green, pink, reddish pink, or even red |
| Crystal habit | Prismatic crystal |
| Cleavage | Perfect |
| Fracture | Subconchoidal to uneven |
| Mohs scale hardness | 8 (defining mineral) |
| Luster | Vitreous |
| Streak | Grayish White |
| Diaphaneity | Transparent |
| Specific gravity | 3.49–3.57 |
From the Wikipedia article
Topaz is a silicate mineral made of aluminum and fluorine with the chemical formula Al2SiO4(F, OH)2. It is used as a gemstone in jewelry and other adornments. Common topaz in its natural state is colorless, though trace element impurities can make it pale blue or golden-brown to yellow-orange. Topaz is often treated with heat or radiation to make it a deep blue, reddish-orange, pale green, pink, or purple.
Source
Source record: crystal-compendium/topaz/minerals.json. Fetched from English Wikipedia by the operator 2 October 2026.
https://en.wikipedia.org/wiki/Topaz — revision id 1373763816. Text and properties from Wikipedia, licensed CC BY-SA 4.0.