Altar Porphyry

In October 2011 Stillwater Mining Company acquired Peregrine Metals Ltd. and its primary asset, the Altar copper-gold exploration mineral property located in the San Juan province of Argentina. Altar is located in the Andes Mountains of Argentina, approximately 10 kilometers from the Argentina-Chile border, and approximately 180 kilometers west of the city of San Juan.

The Altar mineralized system is developed at the unconformable contact of Permo-Triassic Choiyoi Group basement and Tertiary volcanic rocks. The mineral property contains porphyry-style copper and lesser gold and molybdenum mineralization, deposited in an environment that transitions from the basal section of a high-sulphidation epithermal lithocap to a copper porphyry environment.

Stockwork and disseminated copper mineralization is associated with the sericitic and potassic alteration phases, and is hosted in a range of rock types, including porphyry, andesite and andesitic volcanic to hydrothermal breccias.

Altar is primarily a copper-gold porphyry deposit with potential for discrete peripheral gold system targets. The Altar mineral deposit currently exhibits open mineralization in most directions.

Following the purchase of Altar in 2011, the Company further advanced the project in 2012 and 2013 by drilling 38,379 meters of diamond drilling and generating a technical report that summarizes the cumulative drill results of 97,981 meters through 2013. The Company’s 2014/2015 exploration program included prospecting, surface mapping, surface geophysical surveys and the collection of baseline environmental data. The objectives for the 2016 exploration season include a limited exploration program of diamond drilling to test prospecting and geophysical anomalies generated during the 2014/2015 field seasons, plus the continuation of surface mapping and the collection of baseline environmental data.

For more information about Altar, see the most recent Altar Technical Report.

Altar Porphyry