Georgbarsanovite
| Georgbarsanovite | |
|---|---|
| General | |
| Category | Silicate mineral, Cyclosilicate |
| Formula (repeating unit) | Na12(Mn,Sr,REE)3Ca6Fe32+Zr3NbSi25O76Cl2·H2O (original form) |
| Strunz classification |
9.CO.10 (10 ed) 8/E.23-15 (8 ed) |
| Dana classification | 64.1.2.2 |
| Crystal system | Trigonal |
| Crystal class |
Ditrigonal pyramidal (3m) H-M symbol: (3m) |
| Space group | R3m |
| Unit cell | a = 14.26, c = 29.95 [Å] (approximated); Z = 3 |
| Identification | |
| Color | Yellow-green |
| Crystal habit | pseudo-octahedra |
| Cleavage | No |
| Fracture | Uneven |
| Tenacity | Brittle |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent |
| Optical properties | Uniaxial (-) |
| Refractive index | nω 1.64, nε=1.63 (approximated) |
| Pleochroism | green to pale yellow |
| Common impurities | F, K, Y |
| References | [1][2] |
Georgbarsanovite is a very rare mineral of the eudialyte group,[1] formerly known under unaccepted name as barsanovite, with formula Na12(Mn,Sr,REE)3Ca6Fe32+Zr3NbSi(Si3O9)2(Si9O27)2O4Cl2•H2O.[2] The original formula was extended to show the presence of cyclic silicate groups and domination of silicon at the M4 site.[3] "REE", standing for rare earth elements, are dominated by cerium. Georgbarsanovite characterizes in dominance of manganese at the N4 site.[2] It also differs from most other accepted group representatives in its colour. The mineral was found in nepheline pegmatite nearby Petrelius river, Khibiny massif, Kola Peninsula, Russia.[1] It is named after Russian mineralogist Georg Barsanov.[2]
Notes on chemistry
Georgbarsanovite contains admixtures of fluorine, potassium and yttrium, with traces of titanium, hafnium, and barium.[2]
References
- 1 2 3 Mindat, http://www.mindat.org/min-27506.html
- 1 2 3 4 5 Khomyakov, A.P., Nechelyustov, G.N., Ekimenkova, I.A., and Rastsvetayeva, R.K., 2005. Georgbarsanovite, Na12(Mn,Sr,REE)3Ca6Fe32+Zr3NbSi25O76Cl2·H2O, a mineral species of the eudialyte group: revalidation of barsanovite and the new name of the mineral. Zapiski Rossiyskogo Mineralogicheskogo Obshchestva 134(6), 47-57 (in Russian, with English abstract)
- ↑ 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