 Samarium is a rare earth metal having the hardness and density similar to those of zinc . With the boiling point of 1794 ° C , samarium is the third most volatile lanthanide after ytterbium and europium ; this property facilitates separation of samarium from the mineral ore . At ambient conditions , samarium normally assumes a rhombohedral structure ( α form ) . Upon heating to 731 ° C , its crystal symmetry changes into hexagonally close @-@ packed ( hcp ) , however the transition temperature depends on the metal purity . Further heating to 922 ° C transforms the metal into a body @-@ centered cubic ( bcc ) phase . Heating to 300 ° C combined with compression to 40 kbar results in a double @-@ hexagonally close @-@ packed structure ( dhcp ) . Applying higher pressure of the order of hundreds or thousands of <unk> induces a series of phase transformations , in particular with a tetragonal phase appearing at about 900 kbar . In one study , the dhcp phase could be produced without compression , using a <unk> annealing regime with a rapid temperature change between about 400 and 700 ° C , confirming the transient character of this samarium phase . Also , thin films of samarium obtained by vapor deposition may contain the hcp or dhcp phases at ambient conditions . 
