Helium Schuch A F, Grilly E R, Mills R L Physical Review 110 (1958) 775-775 Structure of the alpha and beta forms of solid He Locality: synthetic Sample: at T = 3.3 K & P = .018 GPa Note: structure known as the beta form _database_code_amcsd 0015154 3.46 3.46 5.60 90 90 120 P6_3/mmc atom x y z He 1/3 2/3 .25