Castillo Copper has retracted an announcement titled “Initial pit optimisation delivers A$28m NPV for Big One” after intervention by the ASX.

The announcement on July 13 released details of a preliminary pit optimisation study highlighting the North-West Queensland site’s potential as a standalone mining operation.

The study focused on the near-surface component of known mineralisation at the Big One deposit, which has a mineral resource estimate of 2.1Mt at 1.1 per cent copper for 21,886 tonnes copper metal (inferred).

At the time, Castillo Copper said key findings indicated an initially optimised pit shell could potentially deliver up to 6266 tonnes of copper with a head grade of 1.42 per cent, 4362 oz silver and 1469 tonnes of cobalt.

The company said yesterday it was retracting the announcement following discussions with ASX.

“This information is not consistent with ASX Listing Rules 5.16.6 as the company has based its production targets in the announcement on an inferred resource,” Castillo said.

“As a consequence of the retraction of the announcement, the company advises that investors should not rely on the retracted announcement for their investment decisions.”

The Big One deposit lies about 150km north of Mount Isa, within Castillo’s North-West Queensland copper project, which also includes Arya, Valparaisa, Boomerang and Josephine prospects.

Prime intercepts at Big One have included 40m grading at 1.64 per cent copper from surface including 11m at 4.40 per cent copper from 24m, 5m at 7.34 per cent copper from 28m and 1m at 16.65 per cent copper from 29m downhole.