Fengchengite
Fengchengite is a rare mineral of the eudialyte group[1] with the formula Na
12[ ]
3(Ca,Sr)
6Fe
33+
Zr
3Si(Si
25O
73)(H
2O,OH)
3(OH,Cl)
2.[2][1] The formula is simplified as it does not show the presence of cyclic silicate groups.
When compared to other minerals of the group, fengchengite characterizes in the presence of ferric iron (thus similar to ikranite, mogovidite and feklichevite[1]) and essential, site-dominating vacancies. The mineral was discovered in the Saima complex near Fengcheng city in China - hence its name.[1][2]
| Fengchengite | |
|---|---|
| General | |
| Category | Cyclosilicate |
| Formula (repeating unit) | Na 12[ ] 3(Ca,Sr) 6Fe 33+ Zr 3Si(Si 25O 73)(H 2O,OH) 3(OH,Cl) 2 |
| Crystal system | Trigonal |
| Crystal class | Hexagonal scalenohedral (3m) H-M symbol: (3 2m) |
| Space group | R3m |
| Unit cell | a = 14.25, c = 30.03 [Å] (approximated) |
| Identification | |
| References | [1][2] |
References
- Mindat, Fengchengite, http://www.mindat.org/min-42378.html
- Shen, G., Xu, J., Yao, P., and Li, G., 2011. Fengchengite, IMA 2007-018a. CNMNC Newsletter No. 11, December 2011, 2892; Mineralogical Magazine 75, 2887-2893
Further reading
- Johnsen, O., Ferraris, G., Gault, R.A., Grice, D.G., Kampf, A.R., and Pekov, I.V., 2003. The nomenclature of eudialyte-group minerals. The Canadian Mineralogist 41, 785-794
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