Georgbarsanovite

Georgbarsanovite
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 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]

Notes on chemistry

Georgbarsanovite contains admixtures of fluorine, potassium and yttrium, with traces of titanium, hafnium, and barium.[3]

References

Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
Mindat, http://www.mindat.org/min-27506.html
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

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[1] Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.

[Mindat-2] Mindat, http://www.mindat.org/min-27506.html

[Kh-3] 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)

[4] 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