Among the latest assays from 11 RC holes into the oxide material, Filo reported 68m at 0.74% copper, 1.34g/t gold and 100.1g/t silver from 248m.

CEO Adam Lundin said the results "continue to impress" and would feed into a resource update for a pre-feasibility study underway on the project on the Chile and Argentina border.

A November preliminary economic assessment outlined capex of US$792 million for a 13-year mine producing about 50,000 tonnes of copper, 115,000 ounces of gold and more than 5 million ounces of silver annually.

Lundin said earlier this month Filo was pushing "full steam ahead" with the project and starting to look beyond the horizon of completing the PFS in early 2019.

The company raised C$25.5 million (US$19.9 millon) through a tandem equity raise in February and had just over $18 million (US$14 million) cash at the end of March.

Filo Mining shares closed unchanged yesterday at C$2.30, up from the $1.80 mark it was trading at in May last year.