Author:
Grey I. E.,Keck E.,Mumme W. G.,MacRae C. M.,Price J. R.,Glenn A. M.,Davidson C. J.
Abstract
AbstractCrystals of laueite, Mn2+Fe23+(PO4)2(OH)2·8H2O,
from the Cornelia mine open cut, Hagendorf Süd, Bavaria, are zoned due to
aluminium incorporation at the iron sites, with analysed
Al2O3 contents varying up to 11 wt.%. Synchrotron
X-ray data were collected on two crystals with different Al contents and the
structures refined. The laueite structure contains two independent
Fe3+-containing sites; M2 and
M3, which alternate in 7 Å corner-connected octahedral
chains. The coordination polyhedra are different for the two sites,
M2O4(OH)2 and
M3O2(OH)2(H2O)2
respectively. The structure refinements show that Al preferentially orders
into site M3. Refined site occupancies for
M2 and M3 for the two crystals are: for
crystal L-1, M2 = 0.70(1) Fe + 0.30(1) Al,
M3 = 0.54(1) Fe + 0.46(1) Al and for crystal L-2,
M2 = 0.67(1) Fe + 0.33(1) Al, M3 =
0.48(1) Fe + 0.52(1) Al. For crystal L-2, the octahedral chains have
dominant Fe in M2, alternating with dominant Al in M3 along
the chain, an ordering phenomenon not previously reported for
laueite-related minerals.
Subject
Geochemistry and Petrology
Cited by
2 articles.
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