Mining, Developing & Exploring

Operations / Argentina / Calcatreu

Calcatreu (100% Ownership)

Click here for map of Calcatreu

Pan American Silver became 100% owner of the Calcatreu development project through the acquisition of Aquiline Resources Inc. The property is an advanced exploration-stage, epithermal gold-silver deposit located in the province of Rio Negro, Argentina.

Location and access

Calcatreu is located in the province of Rio Negro, close to the northern boundary of the province of Chubut, approximately 1,250 kilometres southwest of the Argentinean capital city of Buenos Aires. The property is accessed by an unpaved road from the nearest town of Ingeniero Jacobacci (Jacobacci), which is located 60 kilometres north.

Calcatreu lies at an elevation of approximately 1,300 m above sea level and the landscape consists of pampa (treeless grassland or plains) in wide flat valleys between low rocky hills, which support very low intensity sheep farming based on poor quality soil. The project site is devoid of infrastructure except for an unpaved road to Jacobacci.


Geologically, Calcatreu occurs within bimodal calc-alkaline volcanic rocks of the Jurassic Taquetren Formation within the massif. Low sulphidation, epithermal, precious metal-bearing quartz-calcite veining was discovered in the Calcatreu area by La Source in late 1997 when a geologist sampled quartz float that he observed on the roadside while visiting a prospect further to the west. As a result of the assays received and the vein textures noted, two prospecting licenses were staked in 1997, and regional reconnaissance activities commenced the following year.

To date vein systems at 11 prospects have been delineated within the project area. The Vein 49/Nelson system, which has a strike length of over 2 km and widths of up to 20 m, has been the most intensely investigated of these and is the significant discovery at Calcatreu. It is a low sulphidation, quartz adularia gold deposit and its geological setting has strong similarities with the Cerro Vanguardia and El Desquite projects also located in southern Argentina. At certain locations the vein remains open down dip and the structure hosting it remains open along strike.

Mineral resources

At this time, no economic or practical processing route for treating the Calcatreu mineralization is available due to legislative restrictions placed on the use of cyanide by the government of the province of Rio Negro. Therefore, no estimate of a mineral reserve can be made. However, an estimate has been made of the potential mining inventory which may become available in the event that the restrictions are lifted.

The Calcatreu deposit is a Feasibility Stage deposit, with an Initial Feasibility Study ("IFS") published in 2005 by Ausenco Limited. The IFS demonstrated that cyanide is required to deliver proven economics in developing Calcatreu; consequently, development of Calcatreu will require Rio Negro Province to act to remove or modify the existing ban on the use of cyanide in mining.

Current mineral resources at Calcatreu are detailed in the table below:

Calcatreu mineral resource estimate 1

Resource Category Tonnes (Mt) Silver g/t Gold g/t
Indicated 8.0 26 2.63
Inferred 3.4 17 2.06

1. Mineral resources do not have demonstrated economic viability.