Three holes drilled at the Coppermine Creek prospect intersected significant intervals of disseminated chalcopyrite and bands of semi-massive chalcopyrite.
One of the holes returned veins and disseminated chalcopyrite from 38-67m, with the interval from 67-73m corresponding to the Gordons Fault and containing bands of semi-massive chalcopyrite, as well as chalcopyrite fracture fill and disseminations.
The company said the chalcopyrite was associated with only minor pyrite and returned values of more than 25% using a hand-held XRF over widths of up to 30cm.
Assays are expected within a fortnight.
Airborne electromagnetics indicate a 3km by 1km alteration and mineralisation system extending away from the Gordons Fault to the southwest, with further drilling planned to test it.
Pacifico has also started drilling the Bing Bong prospect with the assistance of a NT government grant.
Borroloola West was one of the projects Sandfire floated on in 2004 but the company farmed it out to Pacifico in 2013.
Pacifico expects to earn 51% of the project by the end of the year by spending $A1.5 million under the first phase of the agreement.
The company can earn an additional 19% by spending a further $2.5 million and can get to 80% by sole-funding a bankable feasibility study or spending another $3 million.
Shares in Pacifico jumped 130% to 3.2c, while Sandfire shares gained 1.4% to $5.71.