AM_Sapphirine
Formula: Al9 Mg3.5 Si1.5 O20
Name: Sapphirine
Unit cell: 11.266 14.401 9.929 90.0 125.46 90.0 , V=1312.11
Space group: P121/A1 (14)

Moore P B , American Mineralogist , 54 (1969) p.31-49, The crystal structure of sapphirine