Georgbarsanovite
Mineral of the eudialyte group From Wikipedia, the free encyclopedia
Mineral of the eudialyte group From Wikipedia, the free encyclopedia
Georgbarsanovite is a very rare mineral of the eudialyte group,[2] formerly known under unaccepted name as barsanovite, with formula Na12(Mn,Sr,REE)3Ca6Fe32+Zr3NbSi(Si3O9)2(Si9O27)2O4Cl2·H2O.[3] The original formula was extended to show the presence of cyclic silicate groups and the domination of silicon at the M4 site.[4] "REE", standing for rare earth elements, is dominated by cerium. Georgbarsanovite is characterized in dominance of manganese at the N4 site.[3] It also differs from most other accepted group representatives in its colour. The mineral was found in nepheline pegmatite near Petrelius River, Khibiny massif, Kola Peninsula, Russia.[2] It is named after Russian mineralogist Georg Barsanov.[3]
| Georgbarsanovite | |
|---|---|
Georgbarsanovite | |
| General | |
| Category | Silicate mineral, Cyclosilicate |
| Formula (repeating unit) | Na12(Mn,Sr,REE)3Ca6Fe32+Zr3NbSi25O76Cl2·H2O (original form) |
| IMA symbol | Gba[1] |
| 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) (same H-M symbol) |
| 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 | [2][3] |
Georgbarsanovite contains admixtures of fluorine, potassium and yttrium, with traces of titanium, hafnium, and barium.[3]
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