Yttrium
Wyckoff R W G
Crystal Structures 1 (1963) 7-83
Second edition. Interscience Publishers, New York, New York
Hexagonal closest packed, hcp, structure
_database_code_amcsd 0011199
3.6474 3.6474 5.7306 90 90 120 P6_3/mmc
atom   x   y   z
Y    1/3 2/3 .25