gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1968.036.281.01 The Crystal Structure of Parahopeite Kumbasar Isik 1 Finney J. J. Geology Department, Colorado School of Mines, Golden, Colorado, U.S.A.

Present address: Mining Faculty, Istanbul Technical University, Macka-Istanbul, Turkey.

 3 1968 36 281 621 624 29 8 1967 Copyright © 1968, The Mineralogical Society 1968 Summary

Parahopeite, Zn3(PO4)2.4H2O , is the triclinic dimorph of hopeite. The crystal structure of parahopeite has been determined to be similar to phosphophyllite, Zn2Fe(PO4)2.4H2O and to hopeite in that one of the two zinc atoms is six-coordinated and the other is four-coordinated. Parahopeite differs from the other two minerals though because one of the P-O tetrahedral oxygen atoms is bonded to both the six- and the four-coordinated cations. That is, all four tetrahedral oxygen atoms are bonded to the four-coordinated zinc in parahopeite, whereas in phosphophyllite and hopeite only three of these oxygen atoms are so bonded. 1 Present address: Mining Faculty, Istanbul Technical University, Macka-Istanbul, Turkey.