11 cents, would still be cheapest REE, page-24

Once a grade gets below a certain concentration (eg ~0.3 g/t Au) the mineralisation ceases to be economic. For primary REE deposits the only two significant non-Chinese producers have cut-off grades at the percent level (Mountain Pass quotes 5%). Lower cutoffs may be viable depending on the mix of REE, prices, etc so for example, high Nd_Pr/TREO deposits can support lower cut offs. It is a good idea to look at the grades of the more advanced REE companies as a comparison. It is no coincidence that most of the world’s production from primary REE deposits comes from bastnasite and monazite. Silicates such as allanite are problematic but metallurgical breakthroughs are always possible.