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Letter. Davisite, CaScAlSiO6, a new pyroxene from the Allende meteorite

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Published/Copyright: April 1, 2015
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American Mineralogist
From the journal American Mineralogist Volume 94 Issue 5-6

Abstract

Davisite, ideally CaScAlSiO6, is a new member of the Ca clinopyroxene group, where Sc3+ is dominant in the M1 site. It occurs as micro-sized crystals along with perovskite and spinel in an ultra-refractory inclusion from the Allende meteorite. The mean chemical composition determined by electron microprobe analysis is (wt%) SiO2 26.24, CaO 23.55, Al2O3 21.05, Sc2O3 14.70, TiO2 (total) 8.66, MgO 2.82, ZrO2 2.00, Y2O3 0.56, V2O3 0.55, FeO 0.30, Dy2O3 0.27, Gd2O3 0.13, Er2O3 0.08, sum 100.91. Its empirical formula calculated on the basis of 6 O atoms is Ca0.99(Sc0.50Ti3+0.16Mg0.16Ti4+0.10 Zr0.04V3+0.02Fe2+0.01Y0.01)Σ1.00(Si1.03Al0.97) Σ2.00O6. Davisite is monoclinic, C2/c; a = 9.884 Å, b = 8.988 Å, c = 5.446 Å, β =105.86°, V = 465.39 Å3, and Z = 4. Its electron back-scattered diffraction pattern is an excellent match to that of synthetic CaScAlSiO6 with the C2/c structure. The strongest calculated X-ray powder diffraction lines are [d spacing in Å (I) (hkl)]: 3.039 (100) (2̄21), 2.989 (31) (310), 2.943 (18) (3̄11), 2.619 (40) (002), 2.600 (26) (1̄31), 2.564 (47) (221), 2.159 (18) (3̄31), 2.137 (15) (4̄21), 1.676 (20) (2̄23), and 1.444 (18) (531). The name is for Andrew M. Davis, a cosmochemist at the University of Chicago, Illinois.

Keywords : Davisite; CaScAlSiO6; new mineral; Sc-rich pyroxene; refractory phase; ultra-refractory inclusion; Allende meteorite
Received: 2009-2-4
Accepted: 2009-2-18
Published Online: 2015-4-1
Published in Print: 2009-5-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Closure temperatures of intracrystalline ordering in anatectic and metamorphic hercynite, Fe2+Al2O4
  2. Arsenate substitution in hydroxylapatite: Structural characterization of the Ca5(PxAs1–xO4)3OH solid solution
  3. The crystal chemical role of Zn in alunite-type minerals: Structure refinements for kintoreite and zincian kintoreite
  4. Application of precession electron diffraction to the characterization of (021) twinning in pseudo-hexagonal coesite
  5. Structure, thermodynamic, and transport properties of molten Mg2SiO4: Molecular dynamics simulations and model EOS
  6. High-pressure behavior of åkermanite and gehlenite and phase stability of the normal structure in melilites
  7. Synchrotron-based speciation of chromium in an Oxisol from New Caledonia: Importance of secondary Fe-oxyhydroxides
  8. Meurigite-Na, a new species, and the relationship between phosphofibrite and meurigite
  9. The role of silver on the stabilization of the incommensurately modulated structure in calaverite, AuTe2
  10. Hydrogen zoning in zinc-bearing staurolite from a high-P, low-T diasporite (Samos, Greece): A combined EMP-SIMS-FIB-FTIR study
  11. Dmitryivanovite: A new high-pressure calcium aluminum oxide from the Northwest Africa 470 CH3 chondrite characterized using electron backscatter diffraction analysis
  12. Crystal chemistry of hydrous forsterite and its vibrational properties up to 41 GPa
  13. The geothermobarometric potential of tourmaline, based on experimental and natural data
  14. Inverse spinel structure of Co-doped gahnite
  15. Advances in understanding the structure of borosilicate glasses: A Raman spectroscopy study
  16. The occurrence of tetrahedrally coordinated Al and B in tourmaline: An 11B and 27Al MAS NMR study
  17. Accurate and precise lattice parameters by selected-area electron diffraction in the transmission electron microscope
  18. Two types of metamorphic monazite with contrasting La/Nd, Th, and Y signatures in an ultrahigh-pressure metapelite from the Pohorje Mountains, Slovenia: Indications for pressure-dependent REE exchange between apatite and monazite?
  19. Cs-exchange in birnessite: Reaction mechanisms inferred from time-resolved X-ray diffraction and transmission electron microscopy
  20. Crystal chemistry and radiation-induced amorphization of P-coffinite from the natural fission reactor at Bangombé, Gabon
  21. Letter. Tistarite, Ti2O3, a new refractory mineral from the Allende meteorite
  22. Letter. Davisite, CaScAlSiO6, a new pyroxene from the Allende meteorite
  23. Letter. The 4500 cm–1 infrared absorption band in hydrous aluminosilicate glasses is a combination band of the fundamental (Si,Al)-OH and O-H vibrations
https://doi.org/10.2138/am.2009.3209
Keywords for this article
Davisite; CaScAlSiO6; new mineral; Sc-rich pyroxene; refractory phase; ultra-refractory inclusion; Allende meteorite

Articles in the same Issue

  1. Closure temperatures of intracrystalline ordering in anatectic and metamorphic hercynite, Fe2+Al2O4
  2. Arsenate substitution in hydroxylapatite: Structural characterization of the Ca5(PxAs1–xO4)3OH solid solution
  3. The crystal chemical role of Zn in alunite-type minerals: Structure refinements for kintoreite and zincian kintoreite
  4. Application of precession electron diffraction to the characterization of (021) twinning in pseudo-hexagonal coesite
  5. Structure, thermodynamic, and transport properties of molten Mg2SiO4: Molecular dynamics simulations and model EOS
  6. High-pressure behavior of åkermanite and gehlenite and phase stability of the normal structure in melilites
  7. Synchrotron-based speciation of chromium in an Oxisol from New Caledonia: Importance of secondary Fe-oxyhydroxides
  8. Meurigite-Na, a new species, and the relationship between phosphofibrite and meurigite
  9. The role of silver on the stabilization of the incommensurately modulated structure in calaverite, AuTe2
  10. Hydrogen zoning in zinc-bearing staurolite from a high-P, low-T diasporite (Samos, Greece): A combined EMP-SIMS-FIB-FTIR study
  11. Dmitryivanovite: A new high-pressure calcium aluminum oxide from the Northwest Africa 470 CH3 chondrite characterized using electron backscatter diffraction analysis
  12. Crystal chemistry of hydrous forsterite and its vibrational properties up to 41 GPa
  13. The geothermobarometric potential of tourmaline, based on experimental and natural data
  14. Inverse spinel structure of Co-doped gahnite
  15. Advances in understanding the structure of borosilicate glasses: A Raman spectroscopy study
  16. The occurrence of tetrahedrally coordinated Al and B in tourmaline: An 11B and 27Al MAS NMR study
  17. Accurate and precise lattice parameters by selected-area electron diffraction in the transmission electron microscope
  18. Two types of metamorphic monazite with contrasting La/Nd, Th, and Y signatures in an ultrahigh-pressure metapelite from the Pohorje Mountains, Slovenia: Indications for pressure-dependent REE exchange between apatite and monazite?
  19. Cs-exchange in birnessite: Reaction mechanisms inferred from time-resolved X-ray diffraction and transmission electron microscopy
  20. Crystal chemistry and radiation-induced amorphization of P-coffinite from the natural fission reactor at Bangombé, Gabon
  21. Letter. Tistarite, Ti2O3, a new refractory mineral from the Allende meteorite
  22. Letter. Davisite, CaScAlSiO6, a new pyroxene from the Allende meteorite
  23. Letter. The 4500 cm–1 infrared absorption band in hydrous aluminosilicate glasses is a combination band of the fundamental (Si,Al)-OH and O-H vibrations
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