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Dissakisite-(La) from the Ulten zone peridotite (Italian Eastern Alps): A new end-member of the epidote group

  • Simone Tumiati EMAIL logo , Gaston Godard , Silvana Martin , Paolo Nimis , Volkmar Mair and Bernard Boyer
Published/Copyright: March 28, 2015
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American Mineralogist
From the journal American Mineralogist Volume 90 Issue 7

Abstract

Dissakisite-(La), ideally CaLaAl2MgSi3O12(OH), has been found in the Hochwart peridotite, Ulten zone, Italy. The mineral occurs as centimeter-sized black to very dark brown anhedral nodules and smaller grains. Associated minerals are: olivine, spinel, amphiboles, clino- and orthopyroxenes, and minor clinochlore, uraninite, thorite, thorianite, phlogopite, zircon, apatite, calcite, dolomite, pentlandite, and copper sulfides. The streak is gray-greenish and the luster is vitreous. Mohs hardness is 6.5.7; the mineral is brittle with a conchoidal fracture. The cleavage is imperfect on (001). Dissakisite-(La) is monoclinic, space group P21/m. The unit cell dimensions are a = 8.9616(7), b = 5.7265(5), and c = 10.2353(9) Å, β = 115.193(6)°, V = 475.30(7) Å3, Z = 2. The strongest X-ray powder diffraction lines are: [d(Å) (I)(hkl)] 2.926(100)(113̅), 2.860(53)(020), 2.553(51)(202), 3.526(49)(211̄), 2.699(44)(120). Electron and ion microprobe analysis of the type sample DISS 5 gave the formula (Ca1.195 Mn0.009 Sr0.010 Na0.002 Th0.090 U0.003 La0.315 Ce0.262 Pr 0.019 Nd0.038 Sm0.002 Gd0.001 Er0.001) (Al1.816 Mg0.622 Fe2+0.244 Fe3+0.159 Cr0.148 Ti0.030 Sc0.002 V0.008 Ga0.001 Ni0.010 Zn0.015) (Si2.970 Al0.022 P0.008) O11.991 F0.009 (OH). The La/(La + Ce) ratio is 0.545(16) in the type analysis and 0.543(18) in an average of 70 analyses of the type sample A4310. Ce ≥ La was not observed in any analysis. Dmeas = 3.79(15) g/cm3; Dcalc = 3.84 g/cm3. Radioactivity is appreciable. The optical properties and Raman spectrometry have also been investigated. The mineral formed by hydration and enrichment in LILE and LREE of a peridotite body, in relation to HP-migmatization of the surrounding gneisses during the Variscan orogeny.

Received: 2004-5-13
Accepted: 2004-11-25
Published Online: 2015-3-28
Published in Print: 2005-7-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. A synthesis of systematic mineralogy
  2. Oxidation/alteration of pentlandite and pyrrhotite surfaces at pH 9.3: Part 1. Assignment of XPS spectra and chemical trends
  3. Oxidation of pentlandite and pyrrhotite surfaces at pH 9.3: Part 2. Effect of xanthates and dissolved oxygen
  4. X-ray Rietveld refinement and FTIR spectra of synthetic (Si,Ge)-richterites
  5. Influence of crystal chemistry on ideal plastic shear anisotropy in forsterite: First principle calculations
  6. High-temperature Mössbauer study of Fe-substituted mullite
  7. Pressure and temperature-dependence of water solubility in Fe-free wadsleyite
  8. Quartz exsolution in clinopyroxene is not proof of ultrahigh pressures: Evidence from eclogites from the Eastern Blue Ridge, Southern Appalachians, U.S.A.
  9. The visible and infrared spectral properties of jarosite and alunite
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  11. Compression of albite, NaAlSi3O8
  12. Effect of polymorphic transition on oxygen isotope fractionation between aragonite, calcite, and water: A low-temperature experimental study
  13. Effect of current density on the electron microprobe analysis of alkali aluminosilicate glasses
  14. A high-pressure polytypic transformation in type-I chlorite
  15. Experimental determination of crystal growth rates in highly supercooled aluminosilicate liquids: Implications for rate-controlling processes
  16. P-V equation of State, thermal expansion, and P-T stability of synthetic zincochromite (ZnCr2O4 spinel)
  17. Niksergievite, [Ba1.33Ca0.67Al(CO3)(OH)4][Al2(AlSi3O10)(OH)2]·nH2O, a new phyllosilicate related to the surite-ferrisurite series
  18. The crystal-chemistry of holmquistites: Ferroholmquistite from Greenbushes (Western Australia) and hints for compositional constraints in BLi amphiboles
  19. Dissakisite-(La) from the Ulten zone peridotite (Italian Eastern Alps): A new end-member of the epidote group
  20. Mazzite-Na, a new zeolite from Boron, California: Its description and crystal structure
  21. Low-temperature illitization of smectite in the late eocene and early oligocene of the Isle of Wight (Hampshire basin), U.K.
  22. First reported sedimentary occurrence of berlinite (AlPO4) in phosphate-bearing sediments from Cioclovina Cave, Romania—Comment
  23. Optical and near infrared spectra of ringwoodite to 21.5 GPa: Implications for radiative heat transport in the mantle
  24. Letter. Observation of nano-clustered calcite growth via a transient phase mediated by organic polyanions: A close match for biomineralization
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  26. Letter. Crystal chemistry of a high-pressure C2/c clinopyroxene with six-coordinated silicon
https://doi.org/10.2138/am.2005.1710

Articles in the same Issue

  1. A synthesis of systematic mineralogy
  2. Oxidation/alteration of pentlandite and pyrrhotite surfaces at pH 9.3: Part 1. Assignment of XPS spectra and chemical trends
  3. Oxidation of pentlandite and pyrrhotite surfaces at pH 9.3: Part 2. Effect of xanthates and dissolved oxygen
  4. X-ray Rietveld refinement and FTIR spectra of synthetic (Si,Ge)-richterites
  5. Influence of crystal chemistry on ideal plastic shear anisotropy in forsterite: First principle calculations
  6. High-temperature Mössbauer study of Fe-substituted mullite
  7. Pressure and temperature-dependence of water solubility in Fe-free wadsleyite
  8. Quartz exsolution in clinopyroxene is not proof of ultrahigh pressures: Evidence from eclogites from the Eastern Blue Ridge, Southern Appalachians, U.S.A.
  9. The visible and infrared spectral properties of jarosite and alunite
  10. Wakabayashilite, [(As,Sb)6S9][As4S5]: Crystal structure, pseudosymmetry, twinning, and revised chemical formula
  11. Compression of albite, NaAlSi3O8
  12. Effect of polymorphic transition on oxygen isotope fractionation between aragonite, calcite, and water: A low-temperature experimental study
  13. Effect of current density on the electron microprobe analysis of alkali aluminosilicate glasses
  14. A high-pressure polytypic transformation in type-I chlorite
  15. Experimental determination of crystal growth rates in highly supercooled aluminosilicate liquids: Implications for rate-controlling processes
  16. P-V equation of State, thermal expansion, and P-T stability of synthetic zincochromite (ZnCr2O4 spinel)
  17. Niksergievite, [Ba1.33Ca0.67Al(CO3)(OH)4][Al2(AlSi3O10)(OH)2]·nH2O, a new phyllosilicate related to the surite-ferrisurite series
  18. The crystal-chemistry of holmquistites: Ferroholmquistite from Greenbushes (Western Australia) and hints for compositional constraints in BLi amphiboles
  19. Dissakisite-(La) from the Ulten zone peridotite (Italian Eastern Alps): A new end-member of the epidote group
  20. Mazzite-Na, a new zeolite from Boron, California: Its description and crystal structure
  21. Low-temperature illitization of smectite in the late eocene and early oligocene of the Isle of Wight (Hampshire basin), U.K.
  22. First reported sedimentary occurrence of berlinite (AlPO4) in phosphate-bearing sediments from Cioclovina Cave, Romania—Comment
  23. Optical and near infrared spectra of ringwoodite to 21.5 GPa: Implications for radiative heat transport in the mantle
  24. Letter. Observation of nano-clustered calcite growth via a transient phase mediated by organic polyanions: A close match for biomineralization
  25. Letter. Aluminum coordination and the densification of high-pressure aluminosilicate glasses
  26. Letter. Crystal chemistry of a high-pressure C2/c clinopyroxene with six-coordinated silicon
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