He refers in the article to the Duncan zone. So the winner...

He refers in the article to the Duncan zone. So the winner is:
Lanthanum oxide (La₂O₃): 24.9 %
Cerium oxide (Ce₂O₃): 39.4 %
Praseodymium oxide (Pr₆O₁₁): 4.75 %
Neodymium oxide (Nd₂O₃): 17.9 %
Samarium oxide (Sm₂O₃): 2.83 %
Europium oxide (Eu₂O₃): 0.77 %
Gadolinium oxide (Gd₂O₃): 1.99 %
Terbium oxide (Tb₄O₇): 0.26 %
Dysprosium oxide (Dy₂O₃): 1.27 %
Holmium oxide (Ho₂O₃): 0.19 %
Erbium oxide (Er₂O₃): 0.41 %
Thulium oxide (Tm₂O₃): 0.04 %
Ytterbium oxide (Yb₂O₃): 0.18 %
Special attention should be paid to the high Sm %-age, a REO important for the defence industry and Dy at an exceptional high of 1,27%.