Variety · Quartz group
Smoky quartz
SiO2
Smoky quartz is brown to black quartz coloured by natural radiation acting on trace aluminium; classic sources are the Swiss and Austrian Alps, Colorado's Pikes Peak (with amazonite), Brazil and Scotland's Cairngorms. Alpine smoky quartz with gwindel twists is a connoisseur's mineral. Very dark, uniformly black Brazilian crystals are usually artificially irradiated.
| Formula | SiO2 |
|---|---|
| IMA status | variety |
| Crystal system | Trigonal |
| Mohs hardness | 7 |
| Group | Quartz group |
| Type locality | None (variety) |
Fakes and treatments
Irradiated clear quartz is sold as smoky quartz and is indistinguishable without lab tests; buy from dealers who state the treatment.
Elsewhere
Cite this article
Stratum Strata. "Smoky quartz" (Mineral). Stratum Strata pack 2026.09, as of 2026-09-21. https://stratum.black/strata/minerals/smoky-quartz. Accessed 2026-09-21.
@misc{stratum-smoky-quartz,
title = {Smoky quartz},
author = {{Stratum Strata}},
howpublished = {\url{https://stratum.black/strata/minerals/smoky-quartz}},
year = {2026},
note = {Mineral article, Stratum Strata pack 2026.09, as of 2026-09-21; sources: stratum, wikidata, commons. Accessed 2026-09-21.}
} Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.