ann out , page-42

Its all about certainty,

Mineral reserves dont really exist with any certainty until they are a measured resource. The fact that so much has moved to measured is a good thing.

Billions of tons sound great but only a portion of the copper, molybdenum, gold, etc an be viably extracted. For context I think Oz minerals Prominent Hill had only 8 or so years left in it, making it a 12 year resource at their mining rate. So a large 20 year Yanderra mine has scale. They can and will continue to explore to grow the resource, but at a certain point the effect of additional reserves doesnt greatly effect the viability and NPV of the mine,

Large companies and the Chinese wont invest until they know that the ore is really there and that it can be viably extracted.

At the end of the day its risk/reward, a current producer is less risky but offers orders of magnitude less reward.