Rittmannite, a new mineral species, is the MnMnFe analog of whitelite. It was found in altered phosphatic "modules" from the Mangualde granitic pegmatite (Portugal) as very small (0.3 × 0.3 × 0.04 mm), pale yellow, tabular, pseudohexagonal crystals forming aggregates of subparallel individual crystals. It occurs on kryzhanovskite, frondelite, hureaulite and adularia. Rittmannite is monoclinic, space group P2/a, a 15.01(4), b 6.89(3), c 10.16(3) Å, β 112.82(25)°, V 968(4) Å3. The strongest lines in the x-ray powder-diffraction pattern [d in Å(Iobsd.)(hkl) are: 9.38 (001), 4.69 (002), 2.802 (222). Electron-microprobe data lead to the compn.: MgO 1.5, Al2O3 1.3, CaO 3.3 FeO 10.4, Fe2O3 (calcd.) 2.6, MnO 18.9, P2O5 35.9, H2O (calcd.) 19.7, total 103.6 wt.%, corresponding to the formula: (Mn0.54Ca0.47)Σ1.01Mn1.00(Fe1.152+Mn0.56Mg0.29)Σ2.00(Al1.75Ge0.25)Σ2.00(OH)2.02 (PO4)4.8H2O. The measured and calcd. d. values are 2.81(1) and 2.83 g/cm3, for Z = 2. Rittmannite is biaxial pos., with the orientation of the optical indicatrix: X//b, Z:c + 7°. No pleochroism was obsd.
Rittmannite, a new mineral species of the whiteite group from the Mangualde granitic pegmatite, Portugal / Y., Di Cossato Marzoni Fecia; P., Orlandi; Vezzalini, Maria Giovanna. - In: CANADIAN MINERALOGIST. - ISSN 0008-4476. - STAMPA. - 27:(1989), pp. 447-449.
Rittmannite, a new mineral species of the whiteite group from the Mangualde granitic pegmatite, Portugal
VEZZALINI, Maria Giovanna
1989
Abstract
Rittmannite, a new mineral species, is the MnMnFe analog of whitelite. It was found in altered phosphatic "modules" from the Mangualde granitic pegmatite (Portugal) as very small (0.3 × 0.3 × 0.04 mm), pale yellow, tabular, pseudohexagonal crystals forming aggregates of subparallel individual crystals. It occurs on kryzhanovskite, frondelite, hureaulite and adularia. Rittmannite is monoclinic, space group P2/a, a 15.01(4), b 6.89(3), c 10.16(3) Å, β 112.82(25)°, V 968(4) Å3. The strongest lines in the x-ray powder-diffraction pattern [d in Å(Iobsd.)(hkl) are: 9.38 (001), 4.69 (002), 2.802 (222). Electron-microprobe data lead to the compn.: MgO 1.5, Al2O3 1.3, CaO 3.3 FeO 10.4, Fe2O3 (calcd.) 2.6, MnO 18.9, P2O5 35.9, H2O (calcd.) 19.7, total 103.6 wt.%, corresponding to the formula: (Mn0.54Ca0.47)Σ1.01Mn1.00(Fe1.152+Mn0.56Mg0.29)Σ2.00(Al1.75Ge0.25)Σ2.00(OH)2.02 (PO4)4.8H2O. The measured and calcd. d. values are 2.81(1) and 2.83 g/cm3, for Z = 2. Rittmannite is biaxial pos., with the orientation of the optical indicatrix: X//b, Z:c + 7°. No pleochroism was obsd.
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