A sample of charoitite with frankamenite (Murun Massif, Aldan Shield, Siberia, Russia). The image is published in an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( https://creativecommons.org/licenses/by/4.0/ ). — Photo: Kaneva, E.; Shendrik, R.; Pankrushina, E.; Dokuchits, E.; Radomskaya, T.; Pechurin, M.; Ushakov, A. · CC BY 4.0
Frankamenite
The fluorine-dominant variant of canasite — a triclinic silicate built on octagonal Si₁₂O₃₀ tubes.
Intro adapted from Wikipedia (CC BY-SA).
Frankamenite is an IMA-recognized mineral species in the silicate class, with the chemical formula K₃Na₃Ca₅Si₁₂O₃₀(F,OH)₄·H₂O.
It crystallizes in the triclinic crystal system (space group P1).
Key properties: Mohs hardness 5.5; specific gravity 2.68; refractive index 1.539; optically biaxial.
IMA symbol Fkm, IMA status: approved, named in 1994.