Mn-bearing “oxy-rossmanite” with tetrahedrally coordinated Al and B from Austria: Structure, chemistry, and infrared and optical spectroscopic study
-
Andreas Ertl
,
George R. Rossman
Abstract
Pink, Mn-bearing “oxy-rossmanite” from a pegmatite in a quarry near Eibenstein an der Thaya, Lower Austria, has been characterized by crystal structure determination, chemical analyses (EMPA, SIMS), and optical absorption and infrared spectroscopy. Crystal structure refinements in combination with the chemical analyses give the optimized formulae X(⃞ 0.53Na0.46Ca0.01) Y(Al2.37Li0.33Mn2+0.25Fe2+0.04Ti4+0.01) ZAl6T(Si5.47Al0.28B0.25)O18 (BO3)3 V[(OH)2.85O0.15] W[O0.86(OH)0.10F0.04], with a = 15.8031(3), c = 7.0877(3) Å, and R = 0.017 for the sample with 2.05 wt% MnO, and X(⃞0.53Na0.46Ca0.01) Y(Al2.35Li0.32Mn2+0.28 Fe2+0.04Ti4+0.01) ZAl6T(Si5.51Al0.25B0.24)O18 (BO3)3V[(OH)2.80O0.20] W[O0.86(OH)0.10F0.04] for a sample with a = 15.8171(3), c = 7.0935(2) Å, R = 0.017, and 2.19 wt% MnO. Although the structure refinements show significant amounts of [4]B, the <T-O> bond-lengths (~1.620 Å) mask the incorporation of [4]B because of the incorporation of [4]Al. The <T-O> distances, calculated using the optimized T site occupancies, are consistent with the measured distances. This “oxy-rossmanite” shows that it is possible to have significant amounts of [4]B and [4]Al in an Al-rich tourmaline. The “oxy-rossmanite” from Eibenstein has the highest known Al content of all natural tourmalines (~47 wt% Al2O3; ~8.6 apfu Al). The nearinfrared spectrum confirms both that hydroxyl groups are present in the Eibenstein tourmaline and that they are present at a lower concentration than commonly found in other lithian tourmalines. The integrated intensity (850 cm-2) of the OH bands in the single-crystal spectrum of “oxy-rossmanite” from Eibenstein is distinctly lower than for other Li-bearing tourmaline samples (970-1260 cm-2) with OH contents >3.0 pfu. These samples fall on the V site = 3 (OH) line in the figure defining covariance of the relationship between the bond-angle distortion (σoct2) of the ZO6 octahedron and the <Y-O> distance. On a bond-angle distortion-<Y-O> distance diagram “oxy-rossmanite” from Eibenstein lies between the tourmalines that contain 3 (OH) at the V site, and natural buergerite, which contains 0.3 (OH) and 2.7 O at the V site. No H could be found at the O1 site by refinement, and the spherical electron density in the difference-Fourier map around the O1 site supports the conclusion that this site is mainly occupied by O. The pink color comes from the band at 555 nm that is associated with Mn3+ produced by natural irradiation of Mn2+. This is the first time a tourmaline is described that has a composition that falls in the field of the previously proposed hypothetical species “oxy-rossmanite”.
© 2015 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- Comparative planetary mineralogy: Valence state partitioning of Cr, Fe, Ti, and V among crystallographic sites in olivine, pyroxene, and spinel from planetary basalts
- The origin of orthopyroxene/biotite + plagioclase coronas from the Bolangir anorthosite complex (India), and implications for reconstructing P-T paths
- Dellaventuraite, NaNa2(MgMn23+Ti4+Li)Si8O22O2, a new anhydrous amphibole from the Kajlidongri Manganese Mine, Jhabua District, Madhya Pradesh, India
- Successive zoning of Al and H in hydrothermal vein quartz
- The Ti-saturation surface for low-to-medium pressure metapelitic biotites: Implications for geothermometry and Ti-substitution mechanisms
- Thermochemistry of hydrotalcite-like phases in the MgO-Al2O3-CO2-H2O system: A determination of enthalpy, entropy, and free energy
- Igneous thermometers and barometers based on plagioclase + liquid equilibria: Tests of some existing models and new calibrations
- Thermodynamic properties of the Tschermak solid solution in Fe-chlorite: Application to natural examples and possible role of oxidation
- Experimental data on the Tschermak substitution in Fe-chlorite
- Nanometer-sized, divalent-Mn, hydrous silicate domains in geothermal brine precipitates
- Geometric crystal chemical models for structural analysis of micas and their stacking polytypes
- Fundamental difference between synthetic powder and natural or synthetic single-crystal 1M micas: Geometric homo-octahedral vs. geometric meso-octahedral sheets
- The crystal structures of synthetic Fe2(SO4)3(H2O)5 and the type specimen of lausenite
- Experimental study of plagioclase rim growth around anorthite seed crystals in rhyodacitic melt
- Luminescence study of defects in synthetic as-grown and HPHT diamonds compared to natural diamonds
- Molar absorptivities of OH and H2O in rhyolitic glass at room temperature and at 400600 °C
- Ordering and elasticity associated with low-temperature phase transitions in lawsonite
- Formation of metastable cubic-perovskite in high-pressure phase transformation of Ca(Mg, Fe, Al)Si2O6
- Oxygen isotope heterogeneities and diffusion profile in composite metamorphic-magmatic garnets from the Pyrenees
- Unmixed spinel in chromitite from the Iwanai-dake peridotite complex, Hokkaido, Japan: A reaction between peridotite and highly oxidized magma in the mantle wedge
- Mn-bearing “oxy-rossmanite” with tetrahedrally coordinated Al and B from Austria: Structure, chemistry, and infrared and optical spectroscopic study
- Geochemical applications of the simple salt approximation to the lattice energies of complex materials
- Letter: A method for controlling alkali-metal oxide activities in one-atmosphere experiments and its application to measuring the relative activity coeficients of NaO0.5 in silicate melts
- Letter: Very low solubility of rutile in H2O at high pressure and temperature, and its implications for Ti mobility in subduction zones
- Letter: Microscopic strain in synthetic pyrope-grossular solid solutions determined by synchrotron X-ray powder diffraction at 5 K: The relationship to enthalpy of mixing behavior
- Letter: Ferrous hydroxy carbonate is a stable transformation product of biogenic magnetite
