Definition
TREO stands for Total Rare Earth Oxide. It is the summation of the concentrations of all the individual rare earth elements (La, Ce, Nd, Pr, etc.) calculated as oxides.
Why it Matters
This is the “Grade” of the mine.
- Low Grade: 0.05% to 0.5% (Often Ionic Clays)
- Medium Grade: 1% to 4% (Typical Hard Rock)
- High Grade: 8% to 10%+ (Mount Weld or Mountain Pass)
Warning: A high TREO doesn’t always mean a valuable mine if the mix is mostly cheap Cerium.