Rare Earth Metals and Their Applications In order of increasing atomic mass, the rare earth metals and some of their common applications are given below. Scandium: Atomic weight 21. Used to strengthen aluminum alloys. Yttrium: Atomic weight 39. Used in superconductors and exotic light sources. Lanthanum: Atomic weight 57. Used in specialty glasses and optics, electrodes and for hydrogen storage. Cerium: Atomic weight 58. Makes an excellent oxidizer, used in oil cracking during petroleum refining and is used for yellow color in ceramics and glass. Praseodymium: Atomic weight 59. Used in magnets, lasers and as green color in ceramics and glass. Neodymium: Atomic weight 60. Used in magnets, lasers and as purple color in ceramics and glass. Promethium: Atomic weight 61. Used in nuclear batteries. Samarium: Atomic weight 62. Used in magnets, lasers and for neutron capture. Europium: Atomic weight 63. Makes colored phosphors, lasers, and merc...