Strontiomelane, SrMn4+6Mn3+2O16, a new mineral species of the cryptomelane group from St. Marcel - Praborna, Aosta Valley, Italy

Nicolas Meisser, Elena Adriana Perseil, JOËL Brugger, Pierre Jacques Chiappero

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18 Citations (Scopus)

Abstract

Strontiomelane is a new mineral species from the Praborna mine near Saint-Marcel, Aosta Valley, Italian Alps. It occurs as small anhedral inclusions (about 100-200 μm) and veinlets associated with braunite, cryptomelane, hollandite, quartz, fluorapatite, titanite, jadeite and strontiopiemontite. The new species is opaque, black with a submetallic luster and a strong grey-white pleochroism; in plane-polarized light in oil immersion, it presents a medium anisotropy with grey-blue to white tints. Strontiomelane, whose ideal formula is SrMn4+6Mn3+2O16, crystallizes in space group P21/n(14) with a 10.00(1), b 5.758(7), c 9.88(1) Å, β 90.64(6)°and Z = 2. The strongest lines in the X-ray powder pattern [d in Å(I)(hkl)] are: 3.15(100)(103), 3.13(80)(103), 2.409(80)(122), 2.170(60)(320) and 1.556(50)(225). The calculated density is 4.66(1) g·cm-3. Strontiomelane is the Sr end-member of the cryptomelane group. The proposed name is derived from the chemical element strontium and the color black, melas,-anos in Greek.

Original languageEnglish
Pages (from-to)673-678
Number of pages6
JournalCanadian Mineralogist
Volume37
Issue number3
Publication statusPublished - 1 Jun 1999

Keywords

  • Alps
  • Cryptomelane group
  • Italy
  • Manganese oxide
  • Praborna
  • Strontiomelane
  • Strontium

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