Highlights from drilling at the South Block included 2.72m at 45.51g/t gold, 478.86g/t silver, 17.34% copper and 3.71% zinc, within a wider 6.84m at 19.54g/t gold, 223.98g/t silver, 12.19% copper and 3.7% zinc.
Atico said two rigs were active at the project and aiming to grow La Plata's inferred resource comprising 1.9 million tonnes at an average grade of 4.1g/t gold, 49.4g/t silver, 3.3% copper, 4.5% zinc and 0.6% lead.
It said drilling at La Plata and at El Roble in Colombia were both fully funded by its 90%-owned El Roble copper-gold mining operation.
El Roble produced 4.95 million pounds of copper and 2,733 ounces of gold in concentrates in the June quarter, a 57% and 29% increase respectively on a year earlier.
It said last month the increase was due to a full quarter of production, compared with the second quarter last year when the operation was impacted by a miners' strike.
Atico gained La Plata through its 2019 all-scrip acquisition of Toachi Mining.
Atico can earn up to 75% of La Plata and has exercised its first option to acquire the initial 60%.
It had $7.2 million in working capital according to a July presentation.
Its shares (TSXV: ATY) touched a one-year high of C56c intraday before closing up 25.58% to 54c, capitalising it at $64.3 million (US$48.5 million).