Ann: Significant Expansion to Mineralisation at Boda, page-53

Cadia East is 2.5 km long, 600 m wide and 1.9 km deep to give a resourse of 2800Mt at 0.4g Au/t which works out to about 33.7Moz Au.

Using very simple maths based on Boda is currently being 1 km long 400 m wide and 1.1km deep it could be estimated that the resource is 432 Mt. At 0.4 g/t of Au this would be 5.2 Moz Au, 3.9Moz Au at 0.3 g/t Au and 2.6 Moz Au at 0.2 g/t. Boda is still open at depth as well as to the northwest and south, so it is likely that the resource will grow.

I guess the question is at what size does a porphyry become economic to mine?