| Sm2O3/TREO (% min.) | 99.999 | 99.99 | 99.9 | 99 |
| TREO (% min.) | 99.5 | 99 | 99 | 99 |
| Loss On Ignition (% max.) | 0.5 | 0.5 | 1 | 1 |
| Rare Earth Impurities | ppm max. | ppm max. | % max. | % max. |
| Pr6O11/TREO Nd2O3/TREO Eu2O3/TREO Gd2O3/TREO Y2O3/TREO | 3 5 5 5 1 | 50 100 100 50 50 | 0.01 0.05 0.03 0.02 0.01 | 0.03 0.25 0.25 0.03 0.01 |
| Non-Rare Earth Impurities | ppm max. | ppm max. | % max. | % max. |
| Fe2O3 SiO2 CaO Cl- NiO CuO CoO | 2 20 20 50 3 3 3 | 5 50 100 100 10 10 10 | 0.001 0.015 0.02 0.01 | 0.003 0.03 0.03 0.02 |