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Atom Probe Tomography Analysis of Exsolved Mineral Phases
Published on: October 25, 2019
Isokite, CaMg(PO(4))F(0.8)(OH)(0.2), isomorphous with titanite
Hexiong Yang1, Justin Zwick, Robert T Downs
1Department of Geosciences, University of Arizona, 1040 East 4th Street, Tucson, AZ 85721-0077, USA. hyang@u.arizona.edu
Abstract:
This study presents the first structural report of natural isokite (calcium magnesium phosphate fluoride), with the formula CaMg(PO(4))F(0.8)(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 MgO(4)F(2) octahedra that are crosslinked by isolated PO(4) tetrahedra, forming a three-dimensional polyhedral network. The Ca(2+) cations occupy the interstitial sites coordinated by six O atoms and one F anion.
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