| 词条 | Feklichevite |
| 释义 |
| name = Feklichevite | category = Cyclosilicate | image = | imagesize = | alt = | caption = | formula = Na11Ca9(Fe3+,Fe2+)2Zr3Nb[Si25O73](OH,H2O,Cl,O)5 (original form) | strunz = 9.CO.10 | dana = 64.1.7. | system = Trigonal | class = Ditrigonal pyramidal (3m) H-M symbol: (3m) | symmetry = R3m | unit cell = a = 14.26, c = 30.17 [Å] (approximated); Z = 3 | color = Dark brown | colour = | habit = isometric, thick-tabular; grains | twinning = | cleavage = (001), perfect | fracture = | tenacity = Brittle | mohs = 5.5 | luster = Vitreous | streak = Brownish | diaphaneity = Transparent or Translucent | gravity = | density = 2.87 (approximated) | polish = | opticalprop = Uniaxial (+) | refractive = nω=1.61, nε=1.61 (approximated) | birefringence = | pleochroism = None | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = No | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = Mn, F | alteration = | other = | references = [1][2] }}Feklichevite is a rare mineral of the eudialyte group with the formula Na11Ca9(Fe3+,Fe2+)2Zr3NbSi(Si3O9)2(Si9O27)2.[1][2] The original formula was extended to show the presence of cyclic silicate groups and presence of silicon at the M4 site, according to the nomenclature of eudialyte group.[3] When compared to other minerals of the group, feklichevite characterizes in the presence of ferric iron (thus similar to ikranite, mogovidite and fengchengite[2]) and dominance of calcium at the N4 site. Calcium is ordered in the structure and is also present at the M1 site.[1][3] Other iron-bearing minerals of the group are eudialyte, ferrokentbrooksite, georgbarsanovite, khomyakovite, labyrinthite, oneillite and rastsvetaevite, but they rather contain ferrous iron[2] Feklichevite name honors Russian mineralogist and crystallographer, V. G. Feklichev.[1] Occurrence and associationFeklichevite was found in cancrinite syenite vein of pegmatoid type, that occurs in the Kovdor alkaline massif, Kola Peninsula, Russia. Feklichevite coexists with aegirine-diopside, cancrinite, potassic feldspar, pectolite, titanite, hematite, and руrrhоtitе.[1] Notes on chemistryFeklichevite has quite high admixtures of manganese and fluorine, with minor hafnium, strontium, titanium, cerium, and lanthanum.[1] References1. ^1 2 3 4 5 Pekov, I.V., Ekimenkova, I.A., Chukanov, N.V., Rastsvetaeva, R.K., Kononkova, N.N., Pekova, N.A., and Zadov, A.E., 2001. Feklichevite Na11Ca9(Fe3+,Fe2+)2Zr3Nb[Si25O73](OH,H2O,Cl,O)5, a new mineral of the eudialyte group from Kovdor Massif, Kola peninsula. Zapiski Vserossijskogo Mineralogicheskogo Obshchestva 130(3), 55-65 {{silicate-mineral-stub}}2. ^1 2 3 Mindat, Feklichevite, http://www.mindat.org/min-11029.html 3. ^1 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 7 : Cyclosilicates|Sodium minerals|Calcium minerals|Iron minerals|Zirconium minerals|Niobium minerals|Trigonal minerals |
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