AM_Anorthoclase
Formula: (Al Si3) (Na.667 K.333) O8
Name: Anorthoclase
Unit cell: 8.29 12.966 7.151 91.18 116.31 90.14 , V=688.82
Space group: C-1 (2)

Harlow G E , American Mineralogist , 67 (1982) p.975-996, The anorthoclase structures: The effects of temperature and composition, Grande Calderira, Or = 32.5, T = 23 deg C, feldspar