Jörgkellerite, $\mathrm{Na_{3}Mn^{3+}}$$\mathrm{_{3}(PO_{4})}$$\mathrm{_{2}(CO_{3})O_{2}·5H_{2}O}$, a new layered phosphate-carbonate mineral from the Oldoinyo Lengai volcano, Gregory rift, northern Tanzania

Zaitsev, Anatoly N.; Kearsley, Anton; Kirk, Caroline; Britvin, Sergey; Wenzel, Thomas

doi:10.1007/s00710-016-0487-6

Journal Article

PUBDB-2017-02144

Jörgkellerite, $\mathrm{Na_{3}Mn^{3+}}$$\mathrm{_{3}(PO_{4})}$$\mathrm{_{2}(CO_{3})O_{2}·5H_{2}O}$, a new layered phosphate-carbonate mineral from the Oldoinyo Lengai volcano, Gregory rift, northern Tanzania

Zaitsev, A. N. (Corresponding author) ; Britvin, S.Extern* ; Kearsley, A. ; Wenzel, T. ; Kirk, C.

2016
Springer Wien [u.a.]

Mineralogy and petrology 111(3), 373 – 381 (2016) [10.1007/s00710-016-0487-6]

This record in other databases:

Please use a persistent id in citations: doi:10.1007/s00710-016-0487-6

Abstract: Jörgkellerite, ideally Na$_{3}$Mn$^{3+}$$_{3}$(PO$_{4}$)$_{2}$(CO$_{3}$)O$_{2}$·5H$_{2}$O, is a new layered phosphate-carbonate from the Oldoinyo Lengai volcano in the Gregory Rift (northern Tanzania). The mineral occurs as spherulites, up to 200 μm in diameter, consisting of plates up to 10 μm in thickness in shortite-calcite and calcite carbonatites. Jörgkellerite is brown with a vitreous lustre and has a perfect micaceous cleavage on {001}, Mohs hardness is 3. The calculated density is 2.56 g/cm3. Jörgkellerite is uniaxial (-), ω = 1.700(2), ε = 1.625(2) (Na light, 589 nm) with distinct pleochroism: O = dark brown, E = light brown. The empirical formula of the mineral (average of 10 electron microprobe analyses) is (Na$_{2.46}$K$_{0.28}$Ca$_{0.08}$Sr$_{0.04}$Ba$_{0.02}$)$_{Σ2.88}$(Mn$^{3+}_{2.39}$Fe$^{3+}_{0.56}$)$_{Σ2.95}$((PO$_4$)$_{1.95}$(SiO$_4$)$_{0.05}$))$_{Σ2.00}$(CO$_3$)(O$_{1.84}$(OH)$_{0.16}$)$_{Σ2.00}$·5H$_2$O. The oxidation state of Mn has been determined by XANES. Jörgkellerite is trigonal, space group P-3, a = 11.201(2) Å, c = 10.969(2) Å, V = 1191.9(7) Å$^{3}$ and Z = 3. The five strongest powder-diffraction lines [d in Å, (I/I$_o$), (hkl)] are: 10.970 (100) (001), 5.597 (15) (002), 4.993 (8) (111), 2.796 (14) (220) and 2.724 (20) (004). The crystal structure is built up of the layers composed of disordered edge-sharing [MnO6] octahedra. Each fourth Mn site in octahedral layer is vacant that results in appearance of ordered system of hexagonal “holes” occupied by (CO$_3$) groups. The overall composition of the layer can be expressed as [Mn$_3$O$_8$(CO$_3$)]. These manganese-carbonate layers are linked in the third dimension by (PO$_4$) tetrahedra and Na-polyhedra. The origin of jörgkellerite is related to low-temperature oxidative alteration of gregoryite-nyerereite carbonatites.

Classification: