Thulium Spedding F H, Daane A H, Herrmann K W Acta Crystallographica 9 (1956) 559-563 The crystal structures and lattice parameters of high-purity scandium, yttrium and the rare earth metals Locality: synthetic Note: sample 99.9% pure _database_code_amcsd 0009178 3.5375 3.5375 5.5546 90 90 120 P6_3/mmc atom x y z Tm 1/3 2/3 .25