Americium
Wyckoff R W G
Crystal Structures 1 (1963) 7-83
Second edition. Interscience Publishers, New York, New York
Double hexagonal closest packed, dhcp, structure
_database_code_amcsd 0011202
3.474 3.474 11.25 90 90 120 P6_3/mmc
atom   x   y   z
Am1    0   0   0
Am2  1/3 2/3 .75