Ominelite, (Fe,Mg)Al3BSiO9 (Fe2+ analogue of grandidierite), a new mineral from porphyritic granite in Japan
-
Yoshikuni Hiroi
,
Edward S. Grew
Abstract
Ominelite, (Fe,Mg)Al3BSiO9, is the Fe2+ analog of grandidierite. The mineral occurs as elongated and euhedral to equant and anhedral grains in close association with sekaninaite (Fe-dominant analogue of cordierite), garnet, biotite, andalusite, topaz, alkali feldspar, plagioclase, muscovite, quartz, dumortierite, schorl, zircon, ilmenite, apatite, monazite, and pyrite in a porphyritic granite of Miocene age exposed along the Misen River in Tenkawa, Yoshino, Nara Prefecture, Japan (34°12'40''N, 135°53'40''E). Temperatures <700 °C and pressures below 4 kbars are suggested for the formation of ominelite and associated sekaninaite, topaz, andalusite and dumortierite. The Al-rich minerals could be either magmatic or restitic in origin. A representative electron microprobe analysis of ominelite is SiO2 19.34, TiO2 <0.01, Al2O3 48.85, FeO 19.37, MnO 0.43, MgO 1.33, CaO <0.01, P2O5 0.13, B2O3 10.91 wt%, total 100.36 wt%, corresponding to Fe0.85Mg0.10Mn0.02Al3.01B0.99P0.01Si1.01O9. Mohs’ hardness is about 7. No cleavage is observed. Its color is blue, and the streak is pale blue. It is pleochroic X = Z = pale blue-green and Y = colorless. Optically, it is biaxial (-) and, at λ = 589 nm, has α = 1.631 (1), β = 1.654 (1), γ = 1.656 (1), 2VX (meas.) = 31.5 (6)°. Y = c (prism elongation direction). Dispersion is v >> r. Major lines in the powder pattern [d in Å, (I), (hkl)] are 5.57(m)(020), 5.21(vs)(200), 3.73(m)(121), 3.51(m)(130), 2.97(s)(101), 2.79(s)(040), 2.18(s)(150, 421, 312). Space group is Pbnm. Lattice parameters are a = 10.343 (2), b = 11.095 (1), c = 5.7601 (8) Å and V = 661.0(2) Å3, Z = 4, Dcalc = 3.169 g/cm3. Refinement of the structure confirms that ominelite is isostructural with grandidierite with no detectable substitution of Al by Fe3+.
© 2015 by Walter de Gruyter Berlin/Boston
Artikel in diesem Heft
- Study on adsorption of submicrometer gold on kaolinite by quantum chemistry calculations
- Image distortion in scanning probe microscopy
- Multiple length scale growth spirals on metamorphic graphite {001} surfaces studied by atomic force microscopy
- 29Si MAS NMR study of diopside–Ca-Tschermak clinopyroxenes: Detecting both tetrahedral and octahedral Al substitution
- Electron paramagnetic resonance spectroscopic study of synthetic fluorapatite: Part I. Local structural environment and substitution mechanism of Gd3+ at the Ca2 site
- Electron paramagnetic resonance spectroscopic study of synthetic fluorapatite: Part II. Gd3+ at the Ca1 site, with a neighboring Ca2 vacancy
- Determination of the H3BO3 concentration in fluid and melt inclusions in granite pegmatites by laser Raman microprobe spectroscopy
- Analysis of natural H2O + CO2 + NaCl fluid inclusions in the hydrothermal diamond anvil cell
- Thermodynamics of the amphiboles: Ca-Mg-Fe2+ quadrilateral
- Phase boundary between rutile-type and CaCl2-type germanium dioxide determined by in situ X-ray observations
- The nature, formation, and stability of end-member illite: A hypothesis
- Determination of melanterite-rozenite and chalcanthite-bonattite equilibria by humidity measurements at 0.1 MPa
- Pressure-temperature paths from garnet-zoning: Evidence for multiple episodes of thrust burial in the hinterland of the Sevier orogenic belt
- Mineralogical and Mössbauer spectroscopic study of a diopside occurring in the marbles of Andranondambo, southern Madagascar
- Correlations of octahedral cations with OH–, O2–, Cl–, and F– in biotite from volcanic rocks and xenoliths
- H positions in leucophoenicite, Mn7Si3O12(OH)2: A close relative of the hydrous B phases
- Ominelite, (Fe,Mg)Al3BSiO9 (Fe2+ analogue of grandidierite), a new mineral from porphyritic granite in Japan
- Closure in crystal size distributions (CSD), verification of CSD calculations, and the significance of CSD fans
- Icosahedral domain structure of framboidal pyrite
Artikel in diesem Heft
- Study on adsorption of submicrometer gold on kaolinite by quantum chemistry calculations
- Image distortion in scanning probe microscopy
- Multiple length scale growth spirals on metamorphic graphite {001} surfaces studied by atomic force microscopy
- 29Si MAS NMR study of diopside–Ca-Tschermak clinopyroxenes: Detecting both tetrahedral and octahedral Al substitution
- Electron paramagnetic resonance spectroscopic study of synthetic fluorapatite: Part I. Local structural environment and substitution mechanism of Gd3+ at the Ca2 site
- Electron paramagnetic resonance spectroscopic study of synthetic fluorapatite: Part II. Gd3+ at the Ca1 site, with a neighboring Ca2 vacancy
- Determination of the H3BO3 concentration in fluid and melt inclusions in granite pegmatites by laser Raman microprobe spectroscopy
- Analysis of natural H2O + CO2 + NaCl fluid inclusions in the hydrothermal diamond anvil cell
- Thermodynamics of the amphiboles: Ca-Mg-Fe2+ quadrilateral
- Phase boundary between rutile-type and CaCl2-type germanium dioxide determined by in situ X-ray observations
- The nature, formation, and stability of end-member illite: A hypothesis
- Determination of melanterite-rozenite and chalcanthite-bonattite equilibria by humidity measurements at 0.1 MPa
- Pressure-temperature paths from garnet-zoning: Evidence for multiple episodes of thrust burial in the hinterland of the Sevier orogenic belt
- Mineralogical and Mössbauer spectroscopic study of a diopside occurring in the marbles of Andranondambo, southern Madagascar
- Correlations of octahedral cations with OH–, O2–, Cl–, and F– in biotite from volcanic rocks and xenoliths
- H positions in leucophoenicite, Mn7Si3O12(OH)2: A close relative of the hydrous B phases
- Ominelite, (Fe,Mg)Al3BSiO9 (Fe2+ analogue of grandidierite), a new mineral from porphyritic granite in Japan
- Closure in crystal size distributions (CSD), verification of CSD calculations, and the significance of CSD fans
- Icosahedral domain structure of framboidal pyrite
