Gran Colombia Gold Corp. on Oct. 4 announced an underground mineral resource estimate for its Marmato gold-silver project in Colombia of 3.9 million ounces of gold and 22.6 million ounces of silver in the measured and indicated categories contained within 41.2 million tonnes grading 2.9 g/t of gold and 17.0 g/t of silver.
The project also hosts underground inferred resources of 4.2 million ounces of gold and 15.0 million ounces of silver contained within 52.0 million tonnes at 2.5 g/t of gold and 9.0 g/t of silver.
Gran Colombia noted that the estimate uses a higher cutoff of between 1.2 g/t and 1.9 g/t for different mineralization styles as compared to the 0.3 g/t cutoff used in the 2012 resource estimate.
Over the next six months, the company will prepare a preliminary economic assessment targeting higher-grade material with the intention of developing an expanded underground mining operation at Marmato with a minimum 12-year mine life and life-of-mine gold production of more than 1.5 million ounces.
"The deep mineralization at Marmato remains open along strike and at depth and we expect that our 2018 exploration program will include substantial additional drilling to continue expanding our understanding of the total mineral resource potential of the deposit," Gran Colombia Executive co-Chairman Serafino Iacono said.
Meanwhile, the company plans to implement its contract mining model to incorporate production from the ancestral and artisanal miners working within its titles.
The company resumed operations at the Segovia gold project in Colombia on Sept. 1 following a 42-day civil disruption over a dispute related to illegal mines operating within its mining title.