Properties
| Category | Tectosilicate minerals |
|---|---|
| Formula | SiO2 |
| Crystal system | α-quartz: trigonal trapezohedral class 3 2 ; β-quartz: hexagonal 622 |
| Color | Brown, gray, black |
| Crystal habit | 6-sided prism ending in 6-sided pyramid (typical), drusy, fine-grained to microcrystalline, massive |
| Cleavage | {0110} none |
| Fracture | Conchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 7 – lower in impure varieties (defining mineral) |
| Luster | Vitreous – waxy to dull when massive |
| Streak | White |
| Diaphaneity | Transparent to nearly opaque |
| Specific gravity | 2.65; variable 2.59–2.63 in impure varieties |
From the Wikipedia article
Smoky quartz is a brown to black, translucent variety of quartz. It ranges in clarity from almost complete transparency to almost-opaque black crystals. Smoky quartz is popular as a gemstone and as a collectible crystal.
Source
Source record: crystal-compendium/smoky-quartz/minerals.json. Fetched from English Wikipedia by the operator 2 October 2026.
https://en.wikipedia.org/wiki/Smoky_quartz — revision id 1364718303. Text and properties from Wikipedia, licensed CC BY-SA 4.0.