Plomosas Mine Area Summary
The Plomosas Project is located within 5 km of GR Silver’s San Marcial Project in the Rosario Mining District, Sinaloa, bringing additional opportunities for future development of both projects. The Plomosas Project lies in a geological setting similar to the San Dimas Mining District which has produced over 11Moz gold and 600Moz silver along the western edge of the Sierra Madre Occidental. The Plomosas project includes a past-producing Grupo Mexico S.A de C.V. silver (Ag) – gold (Au) – lead (Pb) – zinc (Zn) underground mine (“Plomosas Mine”) inside 8,515 hectares of mining concessions with numerous drilled areas. The combination of infrastructure and data presents upside potential for resource definition and future exploration. The Plomosas Project together with the San Marcial Project provides GR Silver control of 9,764 ha, covering most of the silver-gold-lead-zinc mineralized zones in the eastern section of the Rosario Mining District. The following royalties interest and purchase rights are related to the Plomosas Project, 2% NSR to Corporacion First Majestic [buyback 1% NSR for US$1,000,000] and 1.75% – 3.5% net production and sales royalty to Industrial Minera based on the price of zinc.
The property lies within an erosional window into the regional geology, exposing andesite and andesitic tuffs, rhyodacites and dacites, with associated volcanic breccias and lapilli tuffs of the Lower Volcanic Series, below a thick sequence of silicic ignimbrites.
The mineralization exhibits the alteration, textures, mineralogy and geometry characteristics of a low sulphidation epithermal silver-gold and base metal (lead-zinc) vein/breccia deposit, with banded quartz-carbonate veining accompanied by potassic adularia-sericite and moderate argillic alteration. Multiple phases of mineralization are evident, as shown by the overprinting of sulphide-rich mineralization over previous gold and silver-gold mineralized zones.
Plomosas is located 98 km southeast of Mazatlan (straight line) and 198.5 km by road.
Most of the historically mined zones consist of quartz-galena-sphalerite +/- pyrite-chalcopyrite, magnetite veins and gold-silver rich stockworks. There is evidence of three stages of quartz sulphide mineralized with brecciation associated with the second stage. The various high-grade Au-Ag stockwork systems appear to be low sulphidation epithermal mineralization, related to low angle dilation zones and fault intersections. There is a predominance of gold-rich stockworks in the Ag-Au-base metal vein breccia foot wall and silver-rich in its hanging wall.