X-ray Diffraction Studies of Vivianite, Metavivianite, and Barićite

T. Sameshima, G. S. Henderson, P. M. Black and K. A. Rodgers
Department of Geology, University of Auckland, Private Bag, Auckland, New Zealand

Abstract: Vivianite specimens from various world localities yield X-ray powder patterns of two types: one corresponds with that shown by synthetic Fe3(PO4)2 · 8H2O and is not readily distinguished from that of barićite; the second shows reflections of monoclinic vivianite and triclinic metavivianite along with reflections of a bobierrite-type phase. The triclinic phase occurs as two twin-related lattices with twin plane 110 being the structural equivalent of 010 in the monoclinic phase. The relationship of the bobierrite-type lattice to the other two has not been established. The ternary pattern is produced by some coarse-grained vivianites on natural oxidation. Finer grained vivianites oxidise to an X-ray amorphous state without passing through a triclinic intermediate.

Keywords: X-ray diffraction • vivianite • metavivianite • barićite

Mineralogical Magazine; March 1985 v. 49; no. 350; p. 81-85; DOI: 10.1180/minmag.1985.049.350.11
© 1985, The Mineralogical Society
Mineralogical Society (www.minersoc.org)