Carbonate Replacement deposits (CRD´s) in the Altiplano.

High-Temperature carbonate replacement ores in the Mexican Altiplano are characterized by metals-rich Tertiary intrusive bodies intruding structurally prepared carbonate host rocks, either limestone or dolomite, of Jurassic or Cretaceous age. Mantos, chimneys and pods of massive sulphides are the three principal morphological types and are generally remote from intrusive centers. CRD´s are large systems ranging from 25-100M tonnes of high-grade ores and are significant contributors of silver lead and zinc.

To date, ten CRD in the Altiplano have published resources (all inclusive) for over 1.7M Oz Au, 300M Oz Ag, 3.1B Lb Cu, 147M Lb Mo, 2.4B Lb Pb and 9.6B Lb Zn.

First Majestic’s La Encantada has the largest silver resource with over 92.5M oz Ag at a grade of 213 g/t Ag, while La Platosa from Excellon Resources boasts the higher grade, with 12.3 M oz Ag at a grade of 786 g/t Ag. Other significant properties are Tayahua owned by Frisco with resources of over 970K Oz Au, 57M Oz Ag, 2.7B Lb Cu, and 1.4B Lb Zn at grades of 0.26g/t Au, 15.1 g/t Ag, 1% Cu, and 0.5% Zn, and MAG Silver´s Cinco de Mayo with resources of over 96K oz Au, 52.7M Oz Ag, 785M Lb Pb and 1.7B Lb Zn, at grades of 0.24 g/t Au, 132 g/t Ag, 2.86% Pb and 6.47% Zn.

Pozo Seco (part of Cinco de Mayo property), also owned by MAG Silver, is the only property containing moly resources for over 147.2 M Lb at a grade of 0.13% Mo.

The table below shows tonnages, grades, as well as gold, silver, copper, moly, lead, and zinc resources (all inclusive) for each of these deposits.

carbonate replacement deposits

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