Mineral · Al2SiO5 polymorphs
Kyanite
Al2(SiO4)O
Kyanite is the blue bladed aluminium silicate of metamorphic schists, famous for two hardnesses in one crystal (4.5 along the blade, 7 across it), from Brazil, Nepal, Switzerland (Pizzo Forno) and Graves Mountain, Georgia. Blue blades in quartz from Brazil are cheap; gem-blue Nepalese crystals are pricier. Green and orange kyanite also occur.
| Formula | Al2(SiO4)O |
|---|---|
| IMA status | grandfathered |
| Crystal system | Triclinic |
| Mohs hardness | 4.5–7 (directional) |
| Group | Al2SiO5 polymorphs |
| Type locality | None |
| Streak | White |
| Specific gravity | 3.6 |
| Reference list | IMA List of Minerals (RRUFF) — verify formula and status against the current list |
Elsewhere
Cite this article
Stratum Study. "Kyanite" (Mineral). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/minerals/kyanite. Accessed 2026-09-20.
@misc{stratum-kyanite,
title = {Kyanite},
author = {{Stratum Study}},
howpublished = {\url{https://stratum.black/study/minerals/kyanite}},
year = {2026},
note = {Mineral article, Stratum Study pack 2026.09, as of 2026-09-19; sources: stratum, wikidata, commons. Accessed 2026-09-20.}
} 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.