undervalued, page-11

Your comparison of Nickel resources needs to consider the metallurgy as well.

Without knowing AUZ, I am guessing the key difference is that AUZ's resource is Nickel Sulphide while RMI's is Laterite Nickel (or Nickel Oxide).

Nickel Sulphide is fairly straight forward to process and concentrates are very marketable. Laterites are very complex and typically require massive Capex for processing plants (e.g. Anaconda/Minara) with autoclaves.

This is likely to explain the bulk of the difference you pointed out in the market cap of the two companies (although enterprise value which includes net debt is probably a better measure).