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Geology of Ore Deposits

, Volume 55, Issue 7, pp 587–593 | Cite as

Osumilite-(Mg): Validation as a mineral species and new data

  • N. V. Chukanov
  • I. V. Pekov
  • R. K. Rastsvetaeva
  • S. M. Aksenov
  • D. I. Belakovskiy
  • K. V. Van
  • W. Schüller
  • B. Ternes
Article
  • 67 Downloads

Abstract

Osumilite-(Mg), the Mg-dominant analogue of osumilite, has been approved by the CNMNC IMA as a new mineral species. The holotype sample has been found at Bellerberg, Eifel volcanic area, Germany. Fluorophlogopite, sanidine, cordierite, mullite, sillimanite, topaz, pseudobrookite and hematite are associated minerals. Osumilite-(Mg) occurs as short prismatic or thick tabular hexagonal crystals reaching 0.5 × 1 mm in size in the cavities in basaltic volcanic glasses at their contact with thermally metamorphosed xenoliths of pelitic rocks. The mineral is brittle, with Mohs’ hardness 6.5. Cleavage was not observed. Color is blue to brown. D meas = 2.59(1), D calc = 2.595 g/cm3. No bands corresponding to H2O and OH-groups are in the IR spectrum. Osumilite-(Mg) is uniaxial (+), ω = 1.539(2), ɛ = 1.547(2). The chemical composition (electron microprobe, average of 5 point analyses, wt %) is: 0.08 Na2O, 3.41 K2O, 0.04 CaO, 7.98 MgO, 0.28 MnO, 21.57 Al2O3, 3.59 Fe2O3, 62.33 SiO2, total 99.28. The empirical formula is: (K0.72Na0.03Ca0.01)(Mg1.97Mn0.04)[Al4.21Fe 0.45 3+ Si10.32]O30. The simplified formula is: KMg2Al3(Al2Si10)O10. The crystal structure was refined on a single crystal, R = 0.0294. Osumilite-(Mg) is hexagonal, space group P6/mcc; a = 10.0959(1), c = 14.3282(2)Å, V = 1264.79(6) Å3, Z = 2. The strongest reflections in the X-ray powder diffraction pattern [d, Å I %) (hkl)] are: 7.21 (37) (002), 5.064 (85) (110), 4.137 (45) (112), 3.736 (43) (202), 3.234 (100) (211), 2.932 (42) (114), 2.767 (51) (204). A type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4174/1.

Keywords

Cordierite Octahedral Site Sillimanite Mineral Species Topaz 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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© Pleiades Publishing, Ltd. 2013

Authors and Affiliations

  • N. V. Chukanov
    • 1
  • I. V. Pekov
    • 2
  • R. K. Rastsvetaeva
    • 3
  • S. M. Aksenov
    • 3
  • D. I. Belakovskiy
    • 4
  • K. V. Van
    • 5
  • W. Schüller
    • 6
  • B. Ternes
    • 7
  1. 1.Institute of Problems of Chemical PhysicsRussian Academy of SciencesChernogolovka, Moscow oblastRussia
  2. 2.Faculty of GeologyMoscow State UniversityMoscowRussia
  3. 3.Institute of CrystallographyRussian Academy of SciencesMoscowRussia
  4. 4.Fersman Mineralogical MuseumRussian Academy of SciencesMoscowRussia
  5. 5.Institute of Experimental MineralogyRussian Academy of SciencesChernogolovka, Moscow oblastRussia
  6. 6.AdenauGermany
  7. 7.MayenGermany

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