Lets do some broad calculations5,000m L x 750m W x 200m D x...

Lets do some broad calculations

5,000m L x 750m W x 200m D x density of 4T/m3 = 3BT of ORE

recovery rate of 85%

now assume a grade

Grade @ 10g/T = 25,500kg or 900,000oz of recoverable gold
Grade @ 20g/T = 51,000kg or 1,800,000oz
Grade @ 30g/T = 76,500kg or 2,700,000oz

Recovery rate assumption was taken from previous studies.
http://www.daff.gov.au/__data/assets/pdf_file/0004/50584/neminrls.pdf