Antipa Minerals and Rio Tinto have unveiled a significant resource upgrade for the Calibre gold-copper-silver deposit within their Citadel joint venture in WA’s Paterson Province, which appears increasingly likely to feature in Rio’s plans to develop the nearby Winu copper discovery. 

Antipa (ASX: AZY) and Rio announced on Monday that the Inferred Mineral Resource for Calibre had increased by 62% to 92 million tonnes at 0.72 g/t gold, 0.11% copper and 0.46 g/t silver for 2.1Moz of gold, 103,700t of copper and 1.3Moz of silver, with the update incorporating results from all drilling conducted since the maiden resource was declared in 2017.

Calibre lies approximately 45km from Winu, and while it hasn’t garnered the same headlines, the deposit possesses a number of characteristics that could be seen as superior.

These include a significant high grade component that can be up to 20-30% higher grade in parts than Winu, shallower cover (average of 80m versus 100m) and no supergene copper blanket, which provides a metallurgical recovery advantage.

Rio has given some indication of its intention to prove up Calibre so it can be incorporated into the Winu development plans by pushing for significantly increased exploration budgets over the past two years.

In 2020, the original Citadel JV budget of $9.2 million was expanded to $12.6 million; this year it was set at $13.8 million before the partners agreed to lift it to $24.5 million.

Commenting on the resource upgrade, Antipa managing director Roger Mason said: “This outstanding result confirms that Calibre, which was discovered by Antipa, is a very large scale gold-copper-silver mineral system with significant growth potential.

“The strategic significance of this deposit is supported by this year’s substantial $24.5 million exploration programme, which has the potential to both further increase the project’s resources and enhance development options.”

Rio lifted its interest in the Citadel joint venture from 51% to 65% at the end of March this year when it reached a $25 million expenditure milestone.

Antipa then elected to contribute to joint venture expenditure on a pro-rata basis going forward to maintain its interest at 35%.

The Citadel Project also features the Magnum deposit, which contains an inferred resource of 16Mt at 0.70 g/t gold, 0.37% copper and 1.00 g/t silver for 339,000oz of gold, 57,800t of copper and 511,000oz of silver.

The brownfields component of this year’s exploration programme will focus on testing shallow extensional targets in the southern region of Calibre, where mineralisation remains open in all direction, and in the northern region of Magnum, as well as following up other mineralised trends within 500m of existing resources.

A total of 19,000m of combined reverse circulation and diamond drilling has been budgeted for focusing on the Magnum Dome area, which hosts Calibre and Magnum and the Corker deposit, the Rimfire area and select regional targets including Boxer.

Value in other assets

Antipa also controls 100% of the 144km2 Minyari Dome Project in the Paterson, which contains 723,340 ounces of gold 26,390 tonnes of copper and 233,290 ounces of silver in resources and lies within 35km of Newcrest Mining’s giant Telfer gold mine.

The company is undertaking a significant drilling programme at Minyari Dome this year that is expected to comprise up to 15,000m of RC drilling and 6,000m of diamond drilling.

The Minyari deposit is considered to share similarities with Greatland Gold/Newcrest Mining’s Havieron deposit in the Paterson in that it is hosted in the same rocks and grade and volume of mineralisation appear to be improving at depth.

Antipa has also farmed out portions of its vast Paterson landholding to Newcrest and IGO Limited and exploration funded by those larger parties is progressing on those projects as well.



This story was developed in collaboration with Antipa Minerals, a Stockhead advertiser at the time of publishing.

This story does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.