Running discussion on SP, page-1326

Rough check.

Very crude big triangle of height 450m (left top start to MO18DD07 hole) and 400m base (roughly of MO18DD007) and 200m between 6900 and 7100 = 450m x 400m x 200 / 2 = 18,000,000 m3 (close to yours).

If spod is 3.11g/cc or 3.1 tonnes/m3, that's roughly 50 million tonnes of spod at 1.5%.
At 1.5%, you need say 5 tonnes to make each tonne of concentrated 6% spod, so we get 10 million tonnes of 6% spod (similar to Scarpa).
Selling at $900 per tonne = $9 billion without LCE plant.
All very approximate.