Up to the end of last century, the Sierra Madre del Sur was not particularly known for its gold resources, even if gold bearing prospects were widespread, and a variety of deposits types carried the precious metal. Gold was known in porphyry copper deposits, in skarns, in VMS deposits, in low, intermediate and high sulfidation epithermal style deposits, orogenic style prospects and placers. All that changed with the slow appreciation circa 1988 of strong geophysical anomalies accompanying several old mines, prospects and surface gold anomalies in Guerrero. The first resource was delineated in 1994, and the Guerrero Gold Belt was born. Today the Sierra Madre del Sur hosts published resources of more than 32 million ounces of gold, of which almost 27 million are in the skarns of the Guerrero Gold Belt.
As it happens, almost half of those resources are in just one giant deposit, Goldcorp’s Los Filos-Nukay, with over 15.5 M Oz Au. Torex Gold’s Limón Guajes and Media Luna come next with 5.3 and almost 4 million ounces of gold, and Timmins Gold’s Ana Paula, with 1.9 M Oz Au. Those four skarn deposits in the Guerrero Gold Belt host over 80 percent of the gold resources of the Sierra Madre del Sur. Other deposits with significant resources are the porphyry copper style deposits of El Tepal, with almost 2 M Oz Au and La Verde, with over 700K Oz Au, in Michoacan. VMS deposits are represented by Nyrstar’s Campo Morado in Guerrero, with over 700 K Oz Au, while Tizapa in Mexico State reports over half a million ounces of gold. The rest of the deposits with gold resources are of low sulfidation epithermal affinity, the two more relevant being Fortuna Silver’s San Jose, carrying over 600K Oz Au and El Aguila, from Gold Resource Corp, hosting more than 150 K Oz Au. The potential is there for defining more gold resources, the challenge being to address the security and land access issues that characterize this region.