Earlier quoted context omitted.
See pages 14 and 15 of this presentation: https://mric.jogmec.go.jp/wp-content/uploads/2019/03/seminar... It's mostly light rare earth elements. Over half of it is cerium and most of the rest is lanthanum. Most of the economic value is in the elements that are not cerium or lanthanum. It appears to have about the same proportion of neodymium and praseodymium (valuable light rare earth elements used in magnets) as the…
Also on that slide: "has average 3.14% grade". I assume that doesn't mean the rock consists of 3.14% of the target element, but is 3.14% of whatever ore they're targeting, right?
Ore is by definition the "economically feasible/interesting" subsection of the rock covered by the claim.