I don't know. Was that question tounge-in-cheek?
There are, of course, real life ways to address the question, and it's along the lines of what I used to do for a living. One "merely" needs to discount to a present value a net income stream over 15 years. Now, that 15-year figure changes across an industry a little from time to time, as does the typical discount rate, which is very low at present. Intestingly, the lower the discount rate, the higher the estimated value.
I don't have the mental energy these days to attempt the above process from information that might be gleened from the Rio Tinto/Kennecott Web site. When I say "gleened" I mean guestimated from historical production figures and projected forward for 15 years - not so easy, even in an informal back-of-the-envelope calculation.
But you already understand these things. Still, we are talking big numbers. One rule of thumb some people used back in the 90's was that a well defined deposit should fetch about one percent of in situ value. I keep going back to this when I recall JB's "forward looking statement" about Hay Mountain perhaps being worth up to 100 billion dollars - probably revised "much" higher now based on new and more supportive information.
'Nuff for today. Good night, and best regards,
VP