SiMg2 Wyckoff R W G Crystal Structures 1 (1963) 239-444 Second edition. Interscience Publishers, New York, New York Fluorite structure _database_code_amcsd 0011717 6.39 6.39 6.39 90 90 90 Fm3m atom x y z Si 0 0 0 Mg .25 .25 .25