This book is good -- but it is not a systematic account of the topic. The discussion of valuation formulae in particular is MUCH too complicated to useful for a dolt like me. The system of calculating DCF and NPV can be gotten elsewhere in much clear fashion. If anyone needs a source for this, inbox me. This is NOT the book, if you're looking for something simple, clear, and introductory. I will try Rudenno now.
This is a very good book -- written before the commodity bull began (1991; revised 1998). Basically, stripping it all away, the key seems to be to get the direction of metals prices right (ch. 12), especially when the cycle turns up; and then to learn enough to be able to detect fraud or bullshit in the feasibility studies.
I've got a few books on order, based on recommendations from some knowledgeable people -- here they are:
A fascinating study - not quite systematic - of some of the more obscure aspects of this ever fascinating industry. A very rich book, despite the rather forbidding title.