Helvine Hassan I, Grundy H D American Mineralogist 70 (1985) 186-192 The crystal structures of helvite group minerals, (MnFeZn)8(Be6Si6O24)S2 _database_code_amcsd 0000974 8.291 8.291 8.291 90 90 90 P-43n atom x y z occ U(1,1) U(2,2) U(3,3) U(1,2) U(1,3) U(2,3) Mn .1709 .1709 .1709 .97 .0079 .0079 .0079 .0002 .0002 .0002 O .1407 .1411 .4168 .0109 .0114 .0077 .0024 .0004 -.0024 Be .25 0 .5 .0069 .0093 .0093 0 0 0 Si .25 .5 0 .0062 .0077 .0077 0 0 0 S 0 0 0 .0112 .0112 .0112 0 0 0