Properties
| Category | Tectosilicate minerals |
|---|---|
| Formula | Silica (silicon dioxide, SiO2) |
| Crystal system | Trigonal |
| Color | Purple, violet, dark purple |
| Crystal habit | 6 sided prism ending in 6 sided pyramid (typical) |
| Cleavage | None |
| Fracture | Conchoidal |
| Mohs scale hardness | 7 (lower in impure varieties) |
| Luster | Vitreous/glassy |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.65 constant; variable in impure varieties |
From the Wikipedia article
Amethyst is a violet variety of natural quartz. Ancient Greeks wore amethyst and carved drinking vessels from it in the belief that it would prevent intoxication. Amethyst, a semiprecious stone, is often used in jewelry. It occurs mostly in association with calcite, quartz, smoky quartz, hematite, pyrite, fluorite, goethite, agate, and chalcedony.
Source
Source record: crystal-compendium/amethyst/minerals.json. Fetched from English Wikipedia by the operator 2 October 2026.
https://en.wikipedia.org/wiki/Amethyst — revision id 1377864997. Text and properties from Wikipedia, licensed CC BY-SA 4.0.