Can anyone tell me where to find a benchmark/measurement system...

Can anyone tell me where to find a benchmark/measurement system for resources such as Gold, Silver, Iron, Copper, Nickel, Uranium etc etc etc.

I have a gist of how it all works but not exactly what is a good result and what is a poor result?

For example with gold, obviously the more g's, the better, but what about the depth etc?

Is this just picked up along the way or is there something out there that can be comparable.

Any help on developing my research skills etc would be greatly appreciated!!