Reference:
▪ Grey, I., Keck, E., Kampf, A.R., Mumme, W.G., Macrae, C.M., Gable, R.W., Glenn, A.M., Davidson, C.J. (2017): Steinmetzite, Zn2Fe3+(PO4)2(OH)·3H2O, a new mineral formed from alteration of phosphophyllite at the Hagendorf Süd pegmatite, Bavaria. Mineralogical Magazine, 81, 329–338.
Abstract:
Steinmetzite, ideally Zn2Fe3+(PO4)2(OH)·3H2O, is a new mineral from the Hagendorf-Süd pegmatite, Hagendorf, Oberpfalz, Bavaria, Germany. Steinmetzite was found in a highly oxidized zone of the Cornelia mine at Hagendorf-Süd. It has formed by alteration of phosphophyllite, involving oxidation of the iron and some replacement of Zn by Fe. Steinmetzite lamellae co-exist with an amorphous Fe-rich phosphate in pseudomorphed phosphophyllite crystals. The lamellae are only a few μm thick and with maximum dimension ~50μm. The phosphophyllite pseudomorphs have a milky opaque appearance, often with a glazed yellow to orange weathering rind and with lengths ranging from sub-mm to 1 cm. Associated minerals are albite, apatite, chalcophanite, jahnsite, mitridatite, muscovite, quartz and wilhelmgümbelite. Goethite and cryptomelane are also abundant in the oxidized zone. The calculated density is 2.96 g.cm-3. Steinmetzite is biaxial (-) with measured refractive indices α = 1.642(2), β = 1.659 (calc.), γ = 1.660(2) (white light). 2V(meas) = 27(1)°; orientation is Y ≈ b, X ^c ≈ 27°, with crystals flattened on {010} and elongated on [001]. Pleochroism shows shades of pale brown; Y > X ≈ Z. Electron microprobe analyses (average of 7 crystals) with Fe reported as Fe2O3 and with H2O calculated from the structure gave ZnO 31.1, MnO 1.7, CaO 0.5, Fe2O3 21,0, Al2O3 0.3, P2O5 32.9, H2O 14.1 wt%, total 102.5%. The empirical formula based on 2 P and 12 O, with all iron as ferric and OH adjusted for charge balance is Zn1.65Fe3+ 1.19Mn2 + .11Ca0.03Al3+ 0.02 (PO4)2(OH)1.21·2.79H2O. The simplified formula is Zn2Fe3+ (PO4)2(OH)·3H2O. Steinmetzite is triclinic, P-1, with unit cell parameters: a=10.438(2), b=5.102(1), c=10.546(2) Å, α=91.37(2), β=115.93(2), and γ=94.20(2)°. V=502.7(3) Å3, Z=2. The strongest lines in the X-ray powder diffraction pattern are [dobs in Å (I) (hkl)] 9.313(65) (100), 5.077(38) (010), 4.726(47) (002), 4.657(100) (200), 3.365(55) (-302), 3.071(54) (1-12) and 2.735(48) (-3-12). The structure is related to that of phosphophyllite.
▪ Grey, I., Keck, E., Kampf, A.R., Mumme, W.G., Macrae, C.M., Gable, R.W., Glenn, A.M., Davidson, C.J. (2017): Steinmetzite, Zn2Fe3+(PO4)2(OH)·3H2O, a new mineral formed from alteration of phosphophyllite at the Hagendorf Süd pegmatite, Bavaria. Mineralogical Magazine, 81, 329–338.
Abstract:
Steinmetzite, ideally Zn2Fe3+(PO4)2(OH)·3H2O, is a new mineral from the Hagendorf-Süd pegmatite, Hagendorf, Oberpfalz, Bavaria, Germany. Steinmetzite was found in a highly oxidized zone of the Cornelia mine at Hagendorf-Süd. It has formed by alteration of phosphophyllite, involving oxidation of the iron and some replacement of Zn by Fe. Steinmetzite lamellae co-exist with an amorphous Fe-rich phosphate in pseudomorphed phosphophyllite crystals. The lamellae are only a few μm thick and with maximum dimension ~50μm. The phosphophyllite pseudomorphs have a milky opaque appearance, often with a glazed yellow to orange weathering rind and with lengths ranging from sub-mm to 1 cm. Associated minerals are albite, apatite, chalcophanite, jahnsite, mitridatite, muscovite, quartz and wilhelmgümbelite. Goethite and cryptomelane are also abundant in the oxidized zone. The calculated density is 2.96 g.cm-3. Steinmetzite is biaxial (-) with measured refractive indices α = 1.642(2), β = 1.659 (calc.), γ = 1.660(2) (white light). 2V(meas) = 27(1)°; orientation is Y ≈ b, X ^c ≈ 27°, with crystals flattened on {010} and elongated on [001]. Pleochroism shows shades of pale brown; Y > X ≈ Z. Electron microprobe analyses (average of 7 crystals) with Fe reported as Fe2O3 and with H2O calculated from the structure gave ZnO 31.1, MnO 1.7, CaO 0.5, Fe2O3 21,0, Al2O3 0.3, P2O5 32.9, H2O 14.1 wt%, total 102.5%. The empirical formula based on 2 P and 12 O, with all iron as ferric and OH adjusted for charge balance is Zn1.65Fe3+ 1.19Mn2 + .11Ca0.03Al3+ 0.02 (PO4)2(OH)1.21·2.79H2O. The simplified formula is Zn2Fe3+ (PO4)2(OH)·3H2O. Steinmetzite is triclinic, P-1, with unit cell parameters: a=10.438(2), b=5.102(1), c=10.546(2) Å, α=91.37(2), β=115.93(2), and γ=94.20(2)°. V=502.7(3) Å3, Z=2. The strongest lines in the X-ray powder diffraction pattern are [dobs in Å (I) (hkl)] 9.313(65) (100), 5.077(38) (010), 4.726(47) (002), 4.657(100) (200), 3.365(55) (-302), 3.071(54) (1-12) and 2.735(48) (-3-12). The structure is related to that of phosphophyllite.