Penikisite, BaMg2Al2(PO4) 3(OH)3, isostructural with bjarebyite

Michael G. Bowman, Robert T. Downs, Hexiong Yang

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


The bjarebyite group of minerals, characterized by the general formula BaX 2 Y 2(PO4)3(OH)3, with X = Mg, Fe2+ or Mn 2+, and Y = Al or Fe3+, includes five members: bjarebyite BaMn2+ 2Al2(PO4)3(OH)3, johntomaite BaFe 2+ 2Fe3+ 2(PO4)3(OH)3, kulanite BaFe2+ 2Al2(PO4)3(OH)3, penikisite BaMg2Al2(PO4)3(OH)3, and perloffite BaMn2+ 2Fe3+ 2(PO4)3(OH)3. Thus far, the crystal structures of all minerals in the group, but penikisite, have been determined. The present study reports the first structure determination of penikisite (barium dimagnesium dialuminium triphosphate trihydroxide) using single-crystal X-ray diffraction data of a crystal from the type locality, Mayo Mining District, Yukon Territory, Canada. Penikisite is isotypic with other members of the bjarebyite group with space group P21/m, rather than triclinic (P1 or P-1), as previously suggested. Its structure consists of edge-shared [AlO 3(OH)3] octahedral dimers linking via corners to form chains along [010]. These chains are decorated with PO4 tetrahedra (one of which has site symmetry m) and connected along [100] via edge-shared [MgO5(OH)] octahedral dimers and eleven-coordinated Ba2+ ions (site symmetry m), forming a complex three-dimensional network. O - H⋯O hydrogen bonding provides additional linkage between chains. Microprobe analysis of the crystal used for data collection indicated that Mn substitutes for Mg at the 1.5% (apfu) level.

Original languageEnglish (US)
Pages (from-to)i4-i5
JournalActa Crystallographica Section E: Structure Reports Online
Issue number2
StatePublished - Feb 2013


  • R factor = 0.015
  • T = 293 K
  • data-to-parameter ratio = 16.6
  • disorder in main residue
  • mean σ(P-O) = 0.002Å
  • single-crystal X-ray study
  • wR factor = 0.039

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics


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