Mineral · Oxides
Chrysoberyl
BeAl2O4
Chrysoberyl is beryllium aluminium oxide, hardness 8.5, forming yellow-green tabular crystals and the famous cyclic 'trilling' twins from Espírito Santo (Brazil), Sri Lanka and Myanmar; alexandrite is the colour-change chromium variety from the Urals, Sri Lanka and Brazil, and cymophane is the cat's-eye. Twinned Brazilian crystals are affordable; alexandrite crystals on matrix are very expensive.
| Formula | BeAl2O4 |
|---|---|
| IMA status | grandfathered |
| Crystal system | Orthorhombic |
| Mohs hardness | 8.5 |
| Group | Oxides |
| Type locality | None |
| Streak | White |
| Specific gravity | 3.7 |
| Reference list | IMA List of Minerals (RRUFF) — verify formula and status against the current list |
Fakes and treatments
Synthetic alexandrite (flux and Czochralski) is common in jewellery; colour-change synthetic corundum imitates it.
Elsewhere
Cite this article
Stratum Strata. "Chrysoberyl" (Mineral). Stratum Strata pack 2026.09, as of 2026-09-21. https://stratum.black/strata/minerals/chrysoberyl. Accessed 2026-09-21.
@misc{stratum-chrysoberyl,
title = {Chrysoberyl},
author = {{Stratum Strata}},
howpublished = {\url{https://stratum.black/strata/minerals/chrysoberyl}},
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.