#163
P-31c
Example – Coquimbite, (Fe,Al)2(SO4)3(H2O)9
Named for the locality, Coquimbo province, Chile
Crystal structures and mineral chemistry of hydrated ferric sulfates. I. The crystal structure of Coquimbite
Fang, J.H.; Robinson, P.D.
American Mineralogist (1970) 55, p1534-p1540
http://www.webmineral.com/data/Coquimbite.shtml
AlO6 octahedra (blue)
FeO6 octahedra (brown)
SO4 tetrahedra (yellow)
Water (black)
The Fascination of Crystals and Symmetry 