Highly regarded mining consultants Newexco delivered the results of the survey - the first conducted over Cangai - which has uncovered five large shallow conductors both within, and external, to the line of lode.

The company described the results as a game-changer that could significantly expand the current resource, which sits at 3.2 million tonnes grading 3.35% copper for around 108,000 tonnes of contained copper.

The results share similarities with Sandfire Resources' DeGrussa mine, in that the high-grade supergene oxide ore sits above larger volumes of mineralised sulphides.

Castillo executive director Alan Armstrong described the survey as a "pivotal point" in the company's evolution.

"Indeed this new discovery is timely, as the current drilling campaign moves into full swing," he said.

Based on the results, the company has approved the expansion of the current 2,250m drilling program with full details to be released shortly. Drilling is set to restart imminently.

The company is also planning an airborne EM survey over the project area.

Castillo raised A$3.4 million in an oversubscribed capital raising at 3.2c per share in September, and said it was fully funded to carry out its plans.

Castillo shares reached a four-and-a-half-year high today of 9.2c, before easing back to 7.9c, a 3.95% rise for the session.