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  • 1
    Electronic Resource
    Electronic Resource
    The water content of nepheline (1989)
    Springer
    Mineralogy and petrology 40 (1989), S. 235-240 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Der Wassergehalt von Nephelinen verschiedener Vorkommen wurde über Glühverlustsbestimmung und Einkristall-Infrarotspektroskopie untersucht. Charakteristische Wassergehalte liegen in Nephelinen zwischen 0,2 und 0,5 Gew. %. Das vermutlich in der K-Position liegende H2O-Molekül kommt in verschiedenen kristallographischen Orientierungen vor. Aus dem Spektrum eines Nephelins von Monte Somma ergeben sich zwei Arten der Wasser-Orientierung. Nach Erhitzen des Kristalls auf 350°C entsteht eine dritte Orientierung.
    Notes: Summary The water content of nephelines from various localities were studied through thermal weight loss and single-crystal infrared spectroscopy. Typical water contents in nepheline are on the order of 0.2 to 0.5 wt. . The H2O molecule exists in multiple crystallographic orientations, presumably in the potassium site. Two orientations of water are indicated in the spectrum of nepheline from Monte Somma. When the crystal is heated to 350°C, a third orientation develops.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01164492
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  • 2
    Electronic Resource
    Electronic Resource
    Water in boninite glass and coexisting orthopyroxene: concentration and partitioning (1995)
    Springer
    Contributions to mineralogy and petrology 118 (1995), S. 414-419 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Spectroscopic measurements of water in glass inclusions in pyroxene from boninite samples from the Bonin Islands conclusively document the high (2.8–3.2 wt %) primary water contents of boninite magmas. Associated quenched glass from pillow lava rims have slightly lower (2.2–2.4 wt %) water contents, suggesting that minor amounts of degassing occurred between the time of melt entrapment in the orthopyroxenes and subsequent eruption on the sea floor. Some zonation of molecular water contents in pillow rim glasses was observed. OH contents of the host orthopyroxene phenocrysts were also measured, allowing for the calculation of partition coefficients for water between boninite melt and orthopyroxene. These values (0.003–0.004) for water partitioning between orthopyroxene and mafic melts may help constrain petrogenetic models of mantle-derived magmas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004100050023
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  • 3
    Electronic Resource
    Electronic Resource
    The distribution of hydroxyl in garnets from the subcontinental mantle of southern Africa (1992)
    Springer
    Contributions to mineralogy and petrology 111 (1992), S. 161-178 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract 166 garnets of dominantly mantle origin were analyzed for OH content by infrared (IR) spectroscopy. IR spectra in the 3400–3700 cm-1 region display consistent absorption patterns attributable to OH structurally bound within the garnet crystal, occasionally contaminated by low intensity OH absorptions from microscopic inclusions. The principal structural OH absorption occurs near 3570 cm-1, with the appearance of additional absorptions near 3512 cm-1 and 3650 cm-1 dependent on garnet composition or paragenesis. Samples derive from a wide variety of rock types occurring as xenoliths in kimberlites of southern Africa. OH abundances, using the best currently available calibration, range from less than 1 up to 135 ppm H2O, and increase in the general order as follows: on-craton eclogites〈coarse-granular peridotites〈Ti-rich deformed peridotites〈some off-craton eclogites〈Cr-poor megacrysts. OH abundances in garnet are closely linked to host rock paragenesis and cannot be explained purely by any crystal chemical factors which we have investigated. Cr-poor garnet megacryst nodules display striking inverse correlations between OH contents and Mg/(Mg+Fe) ratios, which we interpret to reflect the progressively increasing water content of the differentiating parental megacryst magmas. OH abundances in garnet megacrysts decrease in the host rock order Group 2 (micaceous) kimberlite〉Group 1 (basaltic) kimberlite〉alnöite〉alkali basalt. The OH contents of common lithospheric granets from coarse peridotites, including several phlogopite-bearing samples are typically less than 20 ppm H2O, for tectonic settings of kimberlites both on and off the Archaean Kaapvaal craton. Ti-rich garnets from deformed peridotites are richer in OH, supporting previous suggestions of association of these xenoliths with putative megacryst magmas. Subcalcic Cr-rich xenocrysts, diamond inclusion garnets and garnets from diamondiferous eclogites have very low OH contents, similar to eclogites and depleted peridotites without macroscopic diamonds. The OH content of southern African peridotite and eclogite garnets are significantly lower on average than those previously examined from the Colorado Plateau diatremes. While details of emplacement-related H mobility in garnets remain to be established, our results suggest that garnets record useful information on the role of water or other hydrous volatile species in petrological processes at their source regions in the mantle. Although garnets do not appear to constitute a large reservoir of mantle hydrogen, the large stability range of OH-bearing garnet in the crust and mantle implies wide applicability as a qualitative hydrobarometer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348949
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  • 4
    Electronic Resource
    Electronic Resource
    A model for the irradiative coloration of smoky feldspar and the inhibiting influence of water (1985)
    Springer
    Physics and chemistry of minerals 12 (1985), S. 324-332 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Radiation-induced smoky color and associatedelectron paramagnetic resonance (EPR) signals develop only in potassium feldspar (KAlSi3O8) free of structurally bound molecular water. Fluid inclusion water does not influence coloration. The integrated intensity of each of the four bands (11,600, 16,200, 19,100, and 27,200 cm−1) in the optical absorption spectra are linearly correlated with the doubly-integrated intensity of a broad, asymmetric first derivative atg eff=2.027 in EPR spectra. In microcline, the EPR pattern is resolved into an asymmetric six-line pattern atg eff=2.024 and a single derivative atg eff=2.009 which, based on analogy to alkali-silicate glass, are due respectively to [SiO4/K+]2+ and a hole shared between two nonbonding oxygens on Si. We propose that structural water inhibits formation of smoky centers in feldspar by releasing atomic hydrogen during irradiation which destroys centers while diffusing towards a stable site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00654342
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  • 5
    Electronic Resource
    Electronic Resource
    Identifying characteristics of charge transfer transitions in minerals (1987)
    Springer
    Physics and chemistry of minerals 14 (1987), S. 94-99 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Criteria used to identify Fe2+-Fe3+ and Fe2+-Ti4+ intervalence charge transfer absorption bands in electronic spectra are reviewed and compared to the characteristics of unperturbed Fe2+ crystal field bands and those that are intensified by interaction with Fe3+. Band energy is the least definitive diagnostic criterion. Changes in band intensity with temperature are also of limited value. Large widths are the most reliable characteristic of charge transfer bands. New optical absorption spectra are presented for euclase, as well as 80 K spectra of rockbridgeite, babingtonite and lazulite. Comparison of optical spectra to magnetic susceptibility measurements for rockbridgeite and babingtonite provides support for recent theories regarding the effect of magnetic coupling on the variation of charge transfer intensity with temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00311152
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  • 6
    Electronic Resource
    Electronic Resource
    Elastic properties of pyrope (1991)
    Springer
    Physics and chemistry of minerals 17 (1991), S. 617-621 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Brillouin spectroscopy was used to measure the single crystal elastic properties of a pure synthetic pyrope and a natural garnet containing 89.9 mol% of the pyrope end member (Mg3Al2Si3O12). The elastic moduli, c ij , of the two samples are entirely consistent and agree with previous estimates of the elastic properties of pyrope based upon the moduli of solid solutions. Our results indicate that the elastic moduli of pyrope end-member are c 11=296.2±0.5, c 12=111.1±0.6, c 44=91.6±0.3, Ks=172.8±0.3, μ=92.0±0.2, all in units of GPa. These results differ by several percent from those reported previously for synthetic pyrope, but are based upon a much larger data set. Although the hydrous components of the two samples from the present study are substantially different, representing both ‘dry’ and ‘saturated’ samples, we find no discernable effect of structurally bound water on the elastic properties. This is due to the small absolute solubility of water in pyrope, as compared with other garnets such as grossular.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00203841
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  • 7
    Electronic Resource
    Electronic Resource
    Fe2+-Ti4+ charge transfer in stoichiometric Fe2+,Ti4+-minerals (1988)
    Springer
    Physics and chemistry of minerals 16 (1988), S. 78-82 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Optical absorption spectra are presented for taramellite, traskite and neptunite, all of which have both Fe2+ and Ti4+ as major elements. The spectra of each of these minerals are dominated by a single, intense absorption band in the 415 to 460 nm region with 7000 to 9000 cm−1 halfwidth. These transitions, assigned to Fe2+-Ti4+ intervalence charge transfer, showed little difference in intensity at 80 and 300 K and have molar absorptivities which range from ∼100 to ∼1300 M−1 cm−1. The Fe2+-Ti4+ absorptions in these standards generally compare well to other mineral spectra in which Fe2+ — Ti4+ intervalence absorption has previously been proposed with the exception of the most cited example, blue corundum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201333
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  • 8
    Electronic Resource
    Electronic Resource
    Hydrogen bonding interactions in phase A [Mg7Si2O8(OH)6] at ambient and high pressure (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 225-233 
    Details
    ISSN: 1432-2021
    Keywords: Key words Hydrogen bonding ; Neutron diffraction ; Dense hydrous magnesium silicate (DHMS) ; Crystal structure ; High pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  Neutron powder diffraction data of phase A (Mg7Si2O8(OH)6) were collected at ambient pressure and 3.2 GPa (calculated from the compressibility of phase A) from the deuterated compound, and the structure was refined using the Rietveld method. The derived crystal structure implies that hydrogen atoms occupy two distinct sites in phase A, both forming hydrogen bonds of different lengths with the same oxygen atom. This picture is supported by IR spectra, which exhibit two absorption bands at 3400 and 3513 cm−1 corresponding to OH stretching vibrations, and proton NMR spectra, which display two peaks with equal intensities and isotropic chemical shifts of 3.7 and 5 ppm. The D-D distance [D(1)-D(2) distance] at ambient pressure was found to be 2.09 ± 0.02 Å from the neutron diffraction data and 2.09 ± 0.05 Å from the NMR spectra. At 3.2 GPa, there is no statistically significant increase in the O-D interatomic distance while the hydrogen bonding interaction D···O appears to increase for one of the hydrogen sites, D(1), which has the stronger hydrogen bonding interaction compared with the other hydrogen, D(2), at ambient pressure. The O-D bond valences, determined indirectly from the D···O distances were 0.86 and 0.91 at ambient pressure, and 0.83 and 0.90 at 3.2 GPa, for D(1) and D(2), respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002690050251
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  • 9
    Electronic Resource
    Electronic Resource
    Orientation and motion of water molecules in cordierite: A proton nuclear magnetic resonance study (1982)
    Springer
    Physics and chemistry of minerals 8 (1982), S. 14-19 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Conventional and solid state proton nuclear magnetic resonance (NMR) techniques have been used to examine water molecules in the channels of a single crystal of cordierite, (Mg, Fe)2Al4Si5O18, as a function of temperature, magnetic field, and orientation. Only one type of water was found rather than water in two distinct rigid orientations which were indicated by earlier infrared spectral studies. However, the measured dipolar splittings indicate that this water is in rapid motion. Shifts in the dipolar doublet due to Fe2+ impurities indicate that the water molecules are not moving among adjacent channel sites along a channel cavity. A two-site hopping model is proposed involving the major residence time spent with the hydrogen-hydrogen vector parallel to the channels, a minor residence time spent with the hydrogen-hydrogen vector perpendicular to the channels, and a short time (〈1 μs) in transit. This model fits both the present NMR data and previously reported infrared absorption data and is compared to previously reported neutron diffraction data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00311157
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  • 10
    Electronic Resource
    Electronic Resource
    Hydrogen speciation in synthetic quartz (1984)
    Springer
    Physics and chemistry of minerals 11 (1984), S. 204-212 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The dominant hydrogen impurity in synthetic quartz is molecular H2O. H-OH groups also occur, but there is no direct evidence for the hydrolysis of Si-O-Si bonds to yield Si-OH HO-Si groups. Molecular H2O concentrations in the synthetic quartz crystals studied range from less than 10 to 3,300 ppm (H/Si), and decrease smoothly by up to an order of magnitude with distance away from the seed. OH− concentrations range from 96 to 715 ppm, and rise smoothly with distance away from the seed by up to a factor of three. The observed OH− is probably all associated with cationic impurities, as in natural quartz. Molecular H2O is the dominant initial hydrogen impurity in weak quartz. The hydrolytic weakening of quartz may be caused by the transformation H2O + Si-O-Si → 2SiOH, but this may be a transitory change with the SiOH groups recombining to form H2O, and the average SiOH concentration remaining very low. Synthetic quartz is strengthened when the H2O is accumulated into fluid inclusions and cannot react with the quartz framework.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00308135
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