Mantos Blancos

Mantos Blancos is an open pit mine located approximately 45 kilometers from the city of Antofagasta, within a one-hour drive of port facilities at Antofagasta and Mejillones. The mine has no on-site accommodation as most of the staff live mainly in Antofagasta city.

Mantos Blancos has been in operation since 1960 and is one of the major copper mines in the Antofagasta region. Since 2020 and as a result of depletion of the oxide Mineral Reserves, processing in the oxide plant substantially decreased and only run of mine “ROM” dump leaching of low-grade was processed.

The Mantos Blancos Concentrator Debottlenecking Development Project (“MBCDP”, or “Mantos Blancos Expansion”) was completed in late 2021 to extend the mine’s life and expand sulphide ore treatment capacity from 4.2 million tonnes per year to 7.3 million tonnes per year (20 thousand tonnes per day). The MBCDP has a 17-year mine life and a new 20,000 tonnes per day (“tpd”) sulphide processing plant is in the final stages of ramp up to sustained design capacity. Mantos Blancos is expected to produce 50 thousand tonnes of copper per year in the first decade of the MBCDP operation.

Mantos Blancos Phase II represents the mine’s next leg of growth, which is analyzing the potential to further increase the concentrator plant’s throughput to at least 27 thousand tonnes per day, by utilizing existing and unused or underutilized process equipment. The plan also includes extending cathode production beyond the current plan to use the existing 60,000 tonnes per year cathode capacity.

Mantos Blancos is a copper-silver deposit located in the Coastal Range of northern Chile, which is an important geomorphological feature because it hosts Cu-Ag-Au stratabound deposits along an early Cretaceous metallogenic belt. The deposit is mainly characterized by pyroclastic and intrusive host rock units. The pyroclastic rock units are mainly andesite, dacite and rhyolite. The geometry of the mineralized bodies is irregular lenses and oxidized copper sulphides

Mantos Blancos has a long history of Mineral Resource discovery and conversion to Mineral Reserves. The deposit’s mineralization is open at depth and several high-potential opportunities for brownfield exploration are known. There is also potential to leverage other opportunities in the district by utilizing excess cathode-production capacity.

Mantos Blancos District and Near-Mine Exploration – Oxides and Sulphides

The Mantos Blancos mine’s geology is well understood and Capstone’s team has a long history of Mineral Resource discovery and conversion into Mineral Reserves. Near-mine opportunities exist to add additional oxides and sulphides Mineral Resources, and to upgrade existing high-grade Inferred Mineral Resources through additional drilling below the current pit limit.

In addition, many mineralized outcrops have been identified at the Rosario prospect, approximately 15 km south of Mantos Blancos. Exploration targets have been identified through the intersection of faults, geological mapping, geophysics and geochemistry, but limited drilling has been performed to date with the most recent activity in 2017 returning the presence of oxide mineralization.

2024 Guidance

Sustaining Capital	$60 million
Capitalized Stripping	$65 million
Expansionary Capital	–

*Key Assumptions: CLP/USD: 875:1, Silver: $23/oz. All figures in USD.