Plomosas Mine Area

Plomosas Mine Area Summary

VRIFY Tour of San Marcial and Plomosas Mine Areas

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The Plomosas Mine Area (“Plomosas Property”) is located within 5 kilometres of GR Silver Mining’s San Marcial Area (“San Marcial Property”) in the Rosario Mining District, Sinaloa, potentially providing opportunities for the synergistic future development of both areas. The Plomosas Property lies in a geological setting similar to that of the San Dimas Mining District, which has produced over 11 million ounces gold and 600 million ounces silver and is also located along the western edge of the Sierra Madre Occidental. The Plomosas Property includes a past-producing silver–gold–lead–zinc (“Ag-Au-Pb-Zn”) underground mine (“Plomosas Mine”), operated by Grupo Mexico S.A de C.V., inside 8,515 hectares of mining concessions with numerous drilled areas. The combination of infrastructure and historical data presents upside potential for resource definition and future exploration. The Plomosas Property, together with the San Marcial Property, provides GR Silver control of 9,764 hectares, covering most of the Ag-Au-Pb-Zn mineralized zones in the eastern portion of the Rosario Mining District. The following royalty interests and purchase rights are related to the Plomosas Property: 2% NSR to Royalty Streaming Mexico S.A. de C.V. with a buyback right on 1% NSR for US$1,000,000 and a 1.75% – 3.5% net production and sales royalty to Industrial Minera México (a subsidiary of Grupo Mexico) based on the price of zinc.

In March 2023, GR Silver announced an updated NI 43-101 mineral resource estimate for the Plomosas Project, incorporating the San Marcial, Plomosas Mine and San Juan-La Colorada Areas. Full details, including the initial mineral resource estimate, are contained in the Technical Report.

See News Release dated May 4, 2023.
Numbers are rounded
* AgEq is calculated from the metal prices and recoveries using the equation AgEq = ((Au grade*Au price*Au Recovery) + (Ag grade*Ag Price*Ag Recovery) + (Pb grade*Pb Price*Pb Recovery) + (Cu grade*Cu Price*Cu Recovery) + (Zn grade*Zn Price*Zn Recovery)) / (Ag Price*Ag Recovery)
(1) Mineral Resources which are not Mineral Reserves, do not have demonstrated economic viability
(2) The estimate of Mineral Resources may be materially affected by environmental, permitting, legal, title, taxation, socio-political, marketing, or other relevant issues
(3) The Inferred Mineral Resource in this estimate has a lower level of confidence than that applied to an Indicated Mineral Resource and must not be converted to a Mineral Reserve. It is reasonably expected that the majority of the Inferred Mineral Resource could be upgraded to an Indicated Mineral Resource with continued exploration
(4) The Mineral Resources were estimated using the Canadian Institute of Mining, Metallurgy and Petroleum (CIM), CIM Standards on Mineral Resources and Reserves, Definitions and Guidelines prepared by the CIM Standing Committee on Reserve Definitions and adopted by the CIM Council


The Plomosas Property is located 98 kilometres southeast of Mazatlán (straight line) or 198 kilometres by road. 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 geometric 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.

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 mineralization, with brecciation associated with the second stage. The various high-grade silver-gold 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 silver-gold-base metal vein breccia footwall, and silver-rich stockworks in its hanging wall.

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