Calcium-beta Wyckoff R W G Crystal Structures 1 (1963) 7-83 Second edition. Interscience Publishers, New York, New York Sample at T = 450 C Hexagonal closest packed, hcp, structure _database_code_amcsd 0011166 3.98 3.98 6.52 90 90 120 P6_3/mmc atom x y z Ca 1/3 2/3 .25