Tugtupite Hassan I, Grundy H D The Canadian Mineralogist 29 (1991) 385-390 The crystal structure and thermal expansion of tugtupite, Na8[Al2Be2Si8O24]Cl2 _database_code_amcsd 0005268 8.640 8.640 8.873 90 90 90 I-4 atom x y z U(1,1) U(2,2) U(3,3) U(1,2) U(1,3) U(2,3) Al 0 1/2 3/4 .0078 .0078 .0074 0 0 0 Be 0 1/2 1/4 .0086 .0086 .0123 0 0 0 Si .0127 .2533 .4958 .0071 .0063 .0086 -.0002 -.0002 -.0003 O1 .1504 .1343 .4417 .0126 .0116 .0128 .0046 .0010 .0001 O2 .3472 .0385 .6488 .0107 .0119 .0132 -.0003 -.0035 -.0004 O3 .4256 .1486 .1377 .0112 .0114 .0135 -.0001 .0005 .0038 Na .1563 .1972 .1818 .0206 .0160 .0199 .0007 .0024 .0012 Cl 0 0 0 .0228 .0228 .0244 0 0 0