georgbarsanovite

{{infobox mineral | name = Georgbarsanovite | category = Silicate mineral, Cyclosilicate | image = Georgbarsanovite.jpg | imagesize = | alt = | caption = Georgbarsanovite | formula = {{chem2|Na12(Mn,Sr,REE)3Ca6Fe3^{2+}Zr3NbSi25O76Cl2*H2O}} (original form) | IMAsymbol = Gba | strunz = 9.CO.10 (10 ed) 8/E.23-15 (8 ed) | dana = 64.1.2.2 | system = Trigonal | class = Ditrigonal pyramidal (3m) (same H-M symbol) | symmetry = R3m | unit cell = a = 14.26, c = 29.95 [Å] (approximated); Z = 3 | color = Yellow-green | colour = | habit = pseudo-octahedra | twinning = | cleavage = No | fracture = Uneven | tenacity = Brittle | mohs = | luster = Vitreous | streak = White | diaphaneity = Transparent | gravity = | density = | polish = | opticalprop = Uniaxial (-) | refractive = nω 1.64, nε=1.63 (approximated) | birefringence = | pleochroism = green to pale yellow | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = F, K, Y | alteration = | other = | references = }} Georgbarsanovite is a very rare mineral of the eudialyte group, formerly known under unaccepted name as barsanovite, with formula {{chem2|Na12(Mn,Sr,REE)3Ca6Fe3^{2+}Zr3NbSi(Si3O9)2(Si9O27)2O4Cl2*H2O}}. The original formula was extended to show the presence of cyclic silicate groups and the domination of silicon at the M4 site. "REE", standing for rare earth elements, is dominated by cerium. Georgbarsanovite is characterized in dominance of manganese at the N4 site. 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. It is named after Russian mineralogist Georg Barsanov.

==Notes on chemistry== Georgbarsanovite contains admixtures of fluorine, potassium and yttrium, with traces of titanium, hafnium, and barium.