#61
Pbca
Example – Hambergite, Be2BO3(OH,F)
Named for Axel Hamberg (1863-1933), Swedish mineralogist and geographer.
Fluorine-hydroxyl variation in hambergite: A crystal-structure study
Locality: Himalaya mine, California, USA
Burns P C, Novak M, Hawthorne F C
The Canadian Mineralogist 33 (1995) 1205-1213
http://webmineral.com/data/Hambergite.shtml
CIF
http://rruff.geo.arizona.edu/AMS/download.php?id=05964.cif&down=cif
BeO/F4 tetrahedra (blue)
BO3 trigonal planar units (pink)
The Fascination of Crystals and Symmetry 