On those assumptions you outlay $2m to get back $6.4m before tax over nearly 20 years. But you have to believe the mine will be successful and sustainably profitable over that period (obviously if it's not profitable it won't stay open for 16 years = no royalties).
In that case, I mean, why not just invest in the fully paid ordinary shares instead? Seems like the upside from current market cap of $6m, in the event the mine is successful and profitable, is a) a lot greater than 300% and b) you won't have to wait 20 years to be fully paid out?
Downside in both cases if the mine is not successful / not economic / not profitable is similar - you lose 100% of your investment - so why not just stick with HVY shares.
