Fengchengite

Fengchengite
General
Category Cyclosilicate
Formula
(repeating unit)		 Na12[]3(Ca,Sr)6Fe33+Zr3Si(Si25O73)(H2O,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]

Fengchengite is a rare mineral of the eudialyte group[1] with the formula Na12[]3(Ca,Sr)6Fe33+Zr3Si(Si25O73)(H2O,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]

References

  1. 1 2 3 4 5 Mindat, Fengchengite, http://www.mindat.org/min-42378.html
  2. 1 2 3 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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