Another way to think about things is that in situ value is a top line number but does not factor in costs to build mines or operate them, whereas the NPV is a bottom line number with all costs and risk factored in. The higher the discount rate the more risk factored in.

The important thing to appreciate is that just taking 5% or 10% or any percent of the in situ could be both too high or too low. The NPV accounts for all factors and is a much more useful way to calculate value.

If the sales number of $8500 or higher is correct and the operarting costs are just average the NPV will be huge. This does not mean someone will pay this amount, but it gives an idea what companies may pay to own ZEN and how high bidding may get if several entities want the company.