Eleventh Annual V. M. Goldschmidt Conference (2001) sess70.pdf
Wednesday, May 23, 2001 CRYSTAL STRUCTURES AND MINERAL BEHAVIOR I 3:55 p.m. Empire Room
Chairs: J. E. Post N. L. Ross D. Veblen
Kirkpatrick R. J. * Kalinichev A. Hou X. Wang J. Noma H. Yu P. Structure and Dynamics of Layered Double Hydroxides: Interlayer and Surface Species [#3270] The combination of NMR spectroscopy and molecular dynamics simulations provides novel insight into the structural environments and dynamical behavior of surface and interlayer anions and water in this important group of phases.
Hou X. * Kirkpatrick R. J. Selenate and Selenite in Mg,Al and Li,Al Layered Double Hydroxides: A Comparative Study of Structure and Dynamics [#3348] Comparison of NMR, XRD, and TGA data for selenate and selenite LiAl2 and Mg3Al -LDHs provides significant new insight into the factors controlling the dynamical and structural behavior of the interlayer and surface anions of this group of phases.
Post J. E. * McKeown D. A. Characterization of Manganese Oxide Mineralogy in Rock Varnish Using X-Ray Absorption Spectroscopy [#3196] X-ray absorption spectroscopy studies of rock varnish indicate that the predominant Mn oxide minerals are todorokite- and/or birnessite-like phases, or a disordered intermediate of the two.
Moyes L. N. * Pattrick R. A. D. Vaughan D. J. Livens F. R. Charnock J. M. Structural Evolution of Amorphous Transition Metal Sulfides [#3062] Energy dispersive X-ray aborption spectroscopy (EDEXAFS) and energy dispersive X-ray diffraction have been used to study the structural development of transition metal sulfides with time.
Bish D. L. * Guthrie G. D. Reynolds R. C. Jr. Modeling Nuetron Diffraction from Disordered Solids: Three-Dimensional Interstratification in Natural Opal-CT [#3909] Constant-wavelength neutron diffraction data (NIST BT-1 diffractometer) for natural opal-CT samples were simulated using a recursive method that models the three-dimensional diffraction patterns from disordered or interstratified structures.
Welch M. D. * Marshall W. G. Ross N. L. Knight K. S. Hydrogen Positions in Leucophoenicite, Mn7Si3O12(OH)2, and a Comparison with the Hydrous B Phases [#3175] H positions in leucophoenicite are compared with those in Phase B and Superhydrous B. δ(OH) and delta(H...O) in the three phases are similar, but δ(H...H) in leucophoenicite (2.16 Å) is much longer and, unlike the hydrous B phases, H disorder is not expected.
Clark C. M. * Hawthorne F. C. Bonding Character of Triangular Boron in Tourmaline [#3015] The (BO3) groups in tourmaline are usually assumed to be relatively constant. We have examined a suite of over 100 tourmalines. These data indicate that the B-O2 and B-O8 bond lengths are not static, but vary according to the chemical composition of the tourmaline. Eleventh Annual V. M. Goldschmidt Conference (2001) sess70.pdf
Neiva A. M. R. * Silva M. M. V. G. Gomes M. E. P. Geochemistry of Tourmaline from Hercynian Granites, Associated Tin, Tungsten and Gold Deposits and Adjacent Metamorphic and Metasomatic Rocks from Northern Portugal [#3116] Hydrothermal tourmaline is richer in Mg and poorer in Fe than magmatic tourmaline from the same area. Schorl and foitite of quartz veins with wolframite are richer in Fe and Fe/(Fe+Mg) and poorer in Mg than dravite and Mg-foitite of gold-quartz veins.