NpOS Wyckoff R W G Crystal Structures 1 (1963) 294-296 Second edition. Interscience Publishers, New York, New York Note: tetragonal PbFCl structure _database_code_amcsd 0011853 3.825 3.825 6.654 90 90 90 P4/nmm atom x y z Np 0 .5 .200 O 0 0 0 S 0 .5 .638