I wonder what assumptions have been made to get to that figure?
Its over a huge area and is often under Mt Roe basalt from memory.Much of it may be uneconomic .The current finds and estimates based on this are where there is an exposed edge of conglomerate from under the Mt Roe basalt- hence not only a high strip ratio, but the worse overburden a miner could encounter.
What is attractive are the nuggets-great for publicity.
The find is also spread over many companies.
https://smallcaps.com.au/pilbara-gold-rush-complete-guide/
BBX's gold is in a ionic form but is just dying to make nuggets under BBX's guiding hand....ah yes,we've already seen some.
Here's an interesting presentation from Mike Jones,the geologist of IPT. He got out of the Pilbara as soon as a good offer came along.Not a good place for a lifestyle company to be.He's now into a possible conglomerate play in Queensland where the overburden is clay and alluvials that have a gold tenor.Mike knew something that the other's didn't,but one of the few geols. with real conglomerate experience e.gNovo thought that they would drill it - Mike said see it and mine it as drill assay is so innacurate. Excavator,truck and gravity plant......but very very hot and dry for much of the year.
Anyway, hope they are successful for Australia's sake but I think that BBX is a better bet.