Isokite, CaMg(PO4)F0.8(OH)0.2, isomorphous with titanite

Hexiong Yang, Justin Zwick, Robert T. Downs, Gelu Costin

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


This study presents the first structural report of natural isokite (calcium magnesium phosphate fluoride), with the formula CaMg(PO4)F0.8(OH)0.2 (i.e. some substitution of OH for F), based on single-crystal X-ray diffraction data. Isokite belongs to the C2/c titanite mineral group, in which Mg is on an inversion centre and the Ca, P and F/OH atoms are on twofold axes. The structure is composed of kinked chains of corner-sharing MgO4F2 octa-hedra that are crosslinked by isolated PO4 tetra-hedra, forming a three-dimensional polyhedral network. The Ca2+ cations occupy the inter-stitial sites, coordinated by six O atoms and one F anion.

Original languageEnglish (US)
Pages (from-to)i89-i90
JournalActa Crystallographica Section C: Crystal Structure Communications
Issue number10
StatePublished - Sep 22 2007
Externally publishedYes

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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