7.520 at 25 o C Samarium was discovered spectroscopically by Lecoq de Boisbaudran in 1879. There are twenty-one known isotopes of samarium, with seven of them occurring naturally.
Samarium is used for carbon-arc lighting for the motion picture industry.
Compounds containing samarium are used in making permanent magnet material, in infrared absorbing optical glass, as sensitizers for phosphors excited in the infrared, and as a neutron absorber in nuclear reactors.