Cusi Mine Complex

Project History

Mining activity in the Cusi area dates back to the 1700s, with historical production estimated to exceed 100 million ounces of silver. The Cusi Mine was acquired by Dia Bras in 2006, which later rebranded as Sierra Metals in 2012. Commercial production under Sierra Metals at Cusi began in 2014.  

In 2017, Sierra Metals discovered the Santa Rosa de Lima vein system—a stockwork vein structure suitable for bulk mining methods. Following this discovery, the mine plan was adjusted to focus on this area. In 2019, the Malpaso Mill, which processes ore from Cusi, was expanded from a capacity of 600 tonnes per day to 1,200 tonnes per day. Despite the expansion, the mill never reached full utilization.  

Operations at the mine were suspended in 2020 due to the COVID-19 pandemic. During this period, exploration drilling identified a downthrown extension at the Promontorio zone. In 2023, Sierra Metals placed the Cusi Mine on care and maintenance, citing low silver prices and a strategic shift toward base metal production at its Bolivar and Yauricocha operations.  

In its final full year of production, Cusi achieved record output of 1.5 million silver equivalent ounces in 2022, with an all-in sustaining cost of $23.20 per ounce. Mill utilization that year was only 63%.

Historic Resources 

As of 2020, the project hosts a historical NI 43-101* compliant global resource of 66Moz at 200 g/t AgEq, with minimal depletion since. The PEA returned a base case NPV of US$64 million (5% discount, $20/oz silver), increasing to over US$200 million at current silver prices. 

Category​	Tonnes​ (x1000)​	Ag​ (g/t)​	Pb​ (%)​	Zn​ (%)​	Au​ (g/t)​	AgEq​ (g/t)​	AgEq​ (M oz)​
Resources​	​	​	​	​	​	​	​
Measured​	850​	213.0​	0.3​	0.3​	0.1​	231.0​	6.3​
Indicated​	4,506​	176.0​	0.5​	0.6​	0.1​	212.0​	30.7​
Measured & Indicated​	5,356​	181.9​	0.5​	0.6​	0.1​	215.0​	37.0​
Inferred​	4,893​	146.0​	0.43​	0.69​	0.18​	183​	28.8​