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Oxy-chromium-dravite, NaCr3(Cr4Mg2)(Si6O18)(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup

  • Ferdinando Bosi EMAIL logo , Leonid Reznitskii and Henrik Skogby
Published/Copyright: April 2, 2015
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American Mineralogist
From the journal American Mineralogist Volume 97 Issue 11-12

Abstract

Oxy-chromium-dravite, NaCr3(Cr4Mg2)(Si6O18)(BO3)3(OH)3O, is a new mineral of the tourmaline supergroup. It is found in metaquartzites of the Pereval marble quarry (Sludyanka, Lake Baikal, Russia) in association with quartz, calcite, chromphyllite, eskolaite, chromite, uvarovite, chromian phlogopite, and pyroxenes of the diopside-kosmochlor series, Cr-bearing tremolite, Cr-bearing titanite, Cr-bearing rutile, and pyrite. Crystals are emerald green, transparent with a vitreous luster, green streak, and conchoidal fracture. Oxy-chromium-dravite has a VHN hardness of 14 540 MPa, a Mohs hardness of approximately 7½, and a calculated density of 3.3 g/cm3. In plane-polarized light, oxy-chromiumdravite is pleochroic (O = dark green, E = yellow green) and uniaxial negative: ω = 1.765(5), ε = 1.715(5). Oxy-chromium-dravite is rhombohedral, space group R3m, with the unit-cell parameters a = 16.1121(3), c = 7.3701(1) Å, V = 1656.95(5) Å3, Z = 3. The chemical characterization resulted in: SiO2 = 31.73, TiO2 = 0.31, B2O3 = 9.35, Al2O3 = 3.61, Cr2O3 = 36.25, V2O3 = 5.81, MgO = 7.49, Na2O = 2.78, K2O = 0.08, F = 0.78, H2O = 2.16, sum 100.01 wt%. The unit formula is

X(Na1.00K0.02)Σ1.02Y(Cr3+1.95V3+0.87Mg0.14Ti4+0.04)Σ3.00Z(Cr3+3.37Al0.69Mg1.93)Σ6.00[T(Si5.90Al0.10)Σ6.00O18]B(BO3)3 V(OH2.67O0.33)Σ3.00W(O0.54F0.46)Σ1.00.

The crystal structure of oxy-chromium-dravite was refined to statistical index R1 for all reflections equal to 1.54% using MoKα X-ray intensity data. Oxy-chromium-dravite is related to chromium-dravite, ideally NaMg3Cr6(Si6O18)(BO3)3(OH)3OH, by the heterovalent substitution Cr3++O2- → Mg2++OH1-.

Keywords : Oxy-chromium-dravite; tourmaline; new mineral species; crystal-structure refinement; electron microprobe
Received: 2012-4-27
Accepted: 2012-8-7
Published Online: 2015-4-2
Published in Print: 2012-11-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Cation ordering over short-range and long-range scales in the MgAl2O4-CuAl2O4 series
  2. Blue spinel crystals in the MgAl2O4-CoAl2O4 series: Part I. Flux growth and chemical characterization
  3. Blue spinel crystals in the MgAl2O4-CoAl2O4 series: Part II. Cation ordering over short-range and long-range scales
  4. CO2 solubility in primitive martian basalts similar to Yamato 980459, the effect of composition on CO2 solubility of basalts, and the evolution of the martian atmosphere
  5. New structural features of the high-pressure synthetic sheet-disilicate Phase-X, K(2–x)Mg2Si2O7Hx
  6. Crystal structure refinements of borate dimorphs inderite and kurnakovite using 11B and 25Mg nuclear magnetic resonance and DFT calculations
  7. Hydrogen-bond system and dehydration behavior of the natural zeolite parthéite
  8. In situ dehydration behavior of zeolite-like cavansite: A single-crystal X-ray study
  9. LREE-redistribution among fluorapatite, monazite, and allanite at high pressures and temperatures
  10. A single-crystal neutron diffraction study of hambergite, Be2BO3(OH,F)
  11. Analyzing water contents in unexposed glass inclusions in quartz crystals
  12. The atomic structure of deuterated boyleite ZnSO4·4D2O, ilesite MnSO4·4D2O, and bianchite ZnSO4·6D2O
  13. Synthesis and crystal chemistry of Fe3+-bearing (Mg,Fe3+)(Si,Fe3+)O3 perovskite
  14. Mixed-layered structure formation during trans-vacant Al-rich illite partial dehydroxylation
  15. Structural regularities in 2M1 dioctahedral micas: The structure modeling approach
  16. Incorporation of Fe and Al in MgSiO3 perovskite: An investigation by 27Al and 29Si NMR spectroscopy
  17. In situ high-temperature Raman and FTIR spectroscopy of the phase transformation of lizardite
  18. Packing systematics and structural relationships of the new copper molybdate markascherite and related minerals
  19. On the origin of sellaite (MgF2)-rich deposits in Mg-poor environments
  20. Edgrewite Ca9(SiO4)4F2-hydroxyledgrewite Ca9(SiO4)4(OH)2, a new series of calcium humite-group minerals from altered xenoliths in the ignimbrite of Upper Chegem caldera, Northern Caucasus, Kabardino-Balkaria, Russia
  21. Whelanite, Cu2Ca6[Si6O17(OH)](CO3)(OH)3(H2O)2, an (old) new mineral from the Bawana mine, Milford, Utah
  22. 2M1-phlogopite from Black Hills (South Australia): The first case of configurational polytype in micas
  23. Oxy-chromium-dravite, NaCr3(Cr4Mg2)(Si6O18)(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup
  24. First-principles study of self-diffusion and viscous flow in diopside (CaMgSi2O6) liquid
  25. Browneite, MnS, a new sphalerite-group mineral from the Zakłodzie meteorite
  26. Mineralogical variation of silica induced by Al and Na in hydrothermal solutions
https://doi.org/10.2138/am.2012.4210
Keywords for this article
Oxy-chromium-dravite; tourmaline; new mineral species; crystal-structure refinement; electron microprobe

Articles in the same Issue

  1. Cation ordering over short-range and long-range scales in the MgAl2O4-CuAl2O4 series
  2. Blue spinel crystals in the MgAl2O4-CoAl2O4 series: Part I. Flux growth and chemical characterization
  3. Blue spinel crystals in the MgAl2O4-CoAl2O4 series: Part II. Cation ordering over short-range and long-range scales
  4. CO2 solubility in primitive martian basalts similar to Yamato 980459, the effect of composition on CO2 solubility of basalts, and the evolution of the martian atmosphere
  5. New structural features of the high-pressure synthetic sheet-disilicate Phase-X, K(2–x)Mg2Si2O7Hx
  6. Crystal structure refinements of borate dimorphs inderite and kurnakovite using 11B and 25Mg nuclear magnetic resonance and DFT calculations
  7. Hydrogen-bond system and dehydration behavior of the natural zeolite parthéite
  8. In situ dehydration behavior of zeolite-like cavansite: A single-crystal X-ray study
  9. LREE-redistribution among fluorapatite, monazite, and allanite at high pressures and temperatures
  10. A single-crystal neutron diffraction study of hambergite, Be2BO3(OH,F)
  11. Analyzing water contents in unexposed glass inclusions in quartz crystals
  12. The atomic structure of deuterated boyleite ZnSO4·4D2O, ilesite MnSO4·4D2O, and bianchite ZnSO4·6D2O
  13. Synthesis and crystal chemistry of Fe3+-bearing (Mg,Fe3+)(Si,Fe3+)O3 perovskite
  14. Mixed-layered structure formation during trans-vacant Al-rich illite partial dehydroxylation
  15. Structural regularities in 2M1 dioctahedral micas: The structure modeling approach
  16. Incorporation of Fe and Al in MgSiO3 perovskite: An investigation by 27Al and 29Si NMR spectroscopy
  17. In situ high-temperature Raman and FTIR spectroscopy of the phase transformation of lizardite
  18. Packing systematics and structural relationships of the new copper molybdate markascherite and related minerals
  19. On the origin of sellaite (MgF2)-rich deposits in Mg-poor environments
  20. Edgrewite Ca9(SiO4)4F2-hydroxyledgrewite Ca9(SiO4)4(OH)2, a new series of calcium humite-group minerals from altered xenoliths in the ignimbrite of Upper Chegem caldera, Northern Caucasus, Kabardino-Balkaria, Russia
  21. Whelanite, Cu2Ca6[Si6O17(OH)](CO3)(OH)3(H2O)2, an (old) new mineral from the Bawana mine, Milford, Utah
  22. 2M1-phlogopite from Black Hills (South Australia): The first case of configurational polytype in micas
  23. Oxy-chromium-dravite, NaCr3(Cr4Mg2)(Si6O18)(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup
  24. First-principles study of self-diffusion and viscous flow in diopside (CaMgSi2O6) liquid
  25. Browneite, MnS, a new sphalerite-group mineral from the Zakłodzie meteorite
  26. Mineralogical variation of silica induced by Al and Na in hydrothermal solutions
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