The Citadel Project area consists of approximately 1,300km2 of highly prospective but largely underexplored Proterozoic stratigraphy in the north of the Paterson Province.

Under the terms of a Farm-in and Joint Venture Agreement announced in October 2015, Rio Tinto can fund up to $60 million of exploration expenditure to earn up to a 75% interest in the project (current joint venture interest is Antipa 49% : 51% Rio Tinto), which hosts the Calibre gold-copper-silver-tungsten deposit, the Magnum gold-copper-silver deposit and several other smaller deposits and promising prospects. Calibre and Magnum contain a combined Mineral Resource of 1.6 million ounces of gold, 127,300 tonnes of copper and 1.2 million ounces of silver.



Calibre was a greenfields discovery made by Antipa in 2012 with the assistance of aerial electromagnetics. The deposit lies 1.5km north-east of the company’s Magnum deposit and 100km north of the Telfer gold-copper-silver mine.

The geological setting of Calibre is Paterson Province Proterozoic aged, predominantly meta-sediment hosted hydrothermal shear, fault and strata/contact controlled precious and/or base metal mineralisation that is typically sulphide bearing. The deposit lies beneath 70-85m of weakly consolidated and lithified cover, largely of Permian age.

Significant intersections returned from drilling at Calibre include:
  • 30.0m at 2.30 g/t Au and 0.20% Cu including
    • 6.0m at 6.99 g/t Au and 0.48% Cu, also including
    • 1.0m at 22.76 g/t Au and 0.26% Cu
  • 85.0m at 1.27 g/t Au and 0.08% Cu including
    • 25.0m at 2.00 g/t Au and 0.19% Cu
  • 105.0m at 1.18 g/t Au and 0.07% Cu including
    • 17.0m at 2.33 g/t Au and 0.21% Cu, also including
    • 6.0m at 4.47 g/t Au and 0.15% Cu and
    • 1.0m at 17.44 g/t Au and 0.29% Cu
  • 20.0m at 2.25 g/t Au and 0.36% Cu including
    • 1.0m at 9.33 g/t Au, 0.21% Cu and 5.7 g/t Ag
  • 50.0m at 1.20 g/t Au and 0.08% Cu.

There is significant potential to materially increase Calibre’s existing Mineral Resource, with the deposit remaining open in most directions.


Magnum is a low grade, high tonnage gold-copper-silver +/- tungsten mineral system 2km long by up to 400m wide and 600m deep. The deposit also hosts significant high grade gold and copper mineralisation in several lenses.

Significant higher grade intersections returned in drilling at Magnum include:
  • 112.0m at 1.92 g/t Au and 0.10% Cu including
    • 15.0m at 14.10 g/t Au and 0.10% Cu
  • 35.0m at 2.45 g/t Au and 0.11% Cu
  • 30.0m at 1.41 g/t Au and 1.59% Cu
  • 18.8m at 0.57 g/t Au and 1.04% Cu
  • 10.0m at 0.64 g/t Au and 1.36% Cu
  • 5.0m at 1.27 g/t Au and 2.43% Cu
  • 4.0m at 6.70 g/t Au and 1.46% Cu
  • 5.0m at 0.17 g/t Au and 1.21% Cu
  • 8.0m at 0.64 g/t Au and 1.00% Cu

Like Calibre, the Magnum system is open in most directions. Significant exploration upside exists with an isolated drill intercept of 1.4m at 1.72 g/t Au, 6.79%Cu and 32.03 g/t Ag returned 600m south of the resource and other untested electromagnetics targets.