Variety · Quartz group
Chalcedony
SiO2
Chalcedony is microcrystalline quartz with a waxy lustre, the material of agate, carnelian, chrysoprase, onyx, jasper and flint. Botryoidal blue chalcedony from Turkey and Namibia, green chrysoprase from Australia and orange carnelian from India are the collector varieties. It takes a fine polish and is the substance of most lapidary work.
| Formula | SiO2 |
|---|---|
| IMA status | variety |
| Crystal system | Trigonal |
| Mohs hardness | 6.5–7 |
| Group | Quartz group |
| Type locality | None (variety) |
Fakes and treatments
Carnelian and chrysoprase are widely dyed or heated; 'black onyx' is almost always dyed chalcedony.
Elsewhere
Cite this article
Stratum Strata. "Chalcedony" (Mineral). Stratum Strata pack 2026.09, as of 2026-09-21. https://stratum.black/strata/minerals/chalcedony. Accessed 2026-09-21.
@misc{stratum-chalcedony,
title = {Chalcedony},
author = {{Stratum Strata}},
howpublished = {\url{https://stratum.black/strata/minerals/chalcedony}},
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.