... . It dramatically decreases the activa Rare is the periodic table of chemical elements in the lanthanide - lanthanum,cerium,praseodymium, neodymium, promethium ... 17 elements, known as the REE (Rare Earth).The general state of rare earth oxides are separated out, and very rare, and ... thus was named rare earth.ultimateanalysis unit of analysis measured value la2o3 % 4.11 cco2 % 1.29 ...