The Guanajuato Mine Complex (GMC) is Great Panther's largest operation in Mexico and includes production from the Guanajuato and San Ignacio underground mines. For the purposes of resource estimation, GMC also includes the El Horcon project as future production from El Horcon would be trucked to the GMC Cata processing plant. 

GMC is located within the Guanajuato district – historically one of Mexico’s most prolific mining districts, with past production of over one billion ounces of silver and four million ounces of gold since the 16th century. The main Guanajuato mines, Cata processing plant and office facilities are situated in the outskirts of the capital city of Guanajuato, in Guanajuato State. These facilities have excellent infrastructure with access via city streets, and an international airport only 30 minutes away. The San Ignacio mine lies approximately eight kilometres to the west and is accessed by a 22-kilometre paved road. Ore from San Ignacio is trucked to the Cata processing plant.

GMC is an underground silver-gold operation that utilizes cut-and-fill mining methods. Numerous deposits are currently being mined with access provided by interconnected ramps, these same ramps connect to a primary ramp which used for ore haulage to the surface. There also exists two additional shafts which are currently on care and maintenance. Ore is processed into a high quality, precious metal-rich concentrate for transportation to smelters overseas. The Cata processing plant, located near the central Cata shaft, consists of the following three segments:

  • three-stage crushing section, producing a (-¼ inch) fine ore mill feed;
  • Grinding section, consisting of three ball mills operated in parallel, and
  • Conventional flotation circuit with a total capacity of 1,000 tonnes per day.

Most of the supplies and skilled labour required for mining and processing at GMC are sourced from the cities of Guanajuato and Leon.

GMC is 100% owned by Great Panther.

Operating Results

  2013 20143 20153 20163 20173 20183 20193
Tonnes ore milled (000's) 222 268 310 321 320 301 188
Ore silver grade (g/t) 169 161 191 163 151 129 116
Ore gold grade (g/t) 2.3 2.03 2.35 2.43 2.41 2.27 2.26
Plant silver recovery (%) 89.7 89.2 88.5 87.9 89.2 87.9 84.7
Plant gold recovery (%) 84.1 90.8 90.2 86.4 86.9 87.1 85.2
Metal production, (000's Ag eq oz)1 2,840 2,193 3,081 2,987 2,892 2,623 1,518
Silver production, (000's oz) 1,711 1,239 1,708 1,473 1,387 1,097 591
Gold production (oz) 15,714 15,906 21,126 21,626 21,501 19,073 11,588
Cash cost / Ag oz (US$)1,2 10.42 11.12 5.77 0.85 4.32 10.23 6.74
  1. Metal production is expressed in terms of silver equivalent ounces, (Ag Eq oz), the formula for which depends on the gold and silver metal prices used in each year and hence are only indicative.
  2. Cash costs per ounce of silver is a non-IFRS measure used by the Company to manage and evaluate operating performance at each of the Company's mines. It comprises the cost of production, cost of concentrate transportation and the cost of smelter and refining charges, net of the by-product credits from the sale of gold. Refer to the "Non-IFRS Measures" in Great Panther’s MD&A.
  3. Includes production from San Ignacio.


The Guanajuato property is situated along the core of the prolific Veta Madre silver-gold structure. The world-class, low-sulphidation epithermal deposits are somewhat unique as they locally demonstrate a vertical depth extent of greater than 600m (this is rare for epithermal deposits and implies a long-lived mineralizing system).

To a certain degree, deep extensions of mineralization can be found by following known deposits down plunge. Great Panther has been successful at discovering new mineralized zones through systematic drilling and a continually improving understanding of the structural controls. In this way, Great Panther has been successful in replacing what it mines each year. Due to the complex nature of the ore, some zones are mined as they are found, without the need (or time) for detailed drilling.

Presently, exploration at the Guanajuato Mine is focused on re-evaluation of the historical mining areas in the upper parts of the epithermal system.  Work, geological mapping, sampling, re-opening old levels, and core drilling with three underground rigs, has been focused on the Los Pozos, Promontorio, and Valenciana areas. 

At the San Ignacio mine, core drilling has been ongoing throughout 2020 with one underground rig focused on resource definition, and one surface rig focused on the evaluating the Purisima vein system between the historical San Ignacio and San Pedro mines.

Reserve & Resource Estimates

When Great Panther acquired GMC in 2005, there were no NI 43-101 compliant resources and the Company had to rehabilitate the mine in order to begin establishing a new resource base. Since then, numerous NI 43-101 technical reports have been completed and filed.

 GMC Mineral Resource Estimates¹

Mine Tonnes Ag (g/t) Au (g/t) Pb (%) Zn (%) Ag
Ag Eq Oz
San Ignacio 314,863 156 3.06 - - 1,574,848 30,984 4,053,537
Guanajuato 256,260 206 1.72 - - 1,693,799 14,131 2,824,256
Total Measured  571,123 178 2.46 - - 3,268,647 45,115 6,877,793
Mine Tonnes Ag (g/t) Au (g/t) Pb (%) Zn (%) Ag (oz) Au (oz) Ag Eq Oz
San Ignacio 71,554 173 2.87 - - 398,172 6,613 927,201
Guanajuato 87,476 199 1.62 - - 560,673 4,553 924,903
Total Indicated    159,030 188 2.18 - - 958,845 11,166 1,852,104
Mine Tonnes Ag (g/t) Au (g/t) Pb (%) Zn (%) Ag (oz) Au (oz) Ag Eq Oz
San Ignacio 386,417 159 3.03 - - 1,973,020 37,597 4,980,738
Guanajuato 343,736 204 1.69 - - 2,254,472 18,684 3,749,160
Total M&I 730,153 180 2.40 - - 4,227,492 56,281 8,729,897
Mine Tonnes Ag (g/t) Au (g/t) Pb (%) Zn (%) Ag (oz) Au (oz) Ag Eq Oz
San Ignacio 501,870 149 2.69 - - 2,405,484 43,398 5,877,391
Guanajuato 208,609 168 2.32 - - 1,129,416 15,561 2,374,341
El Horcón  162,140 76 3.44 2.69 3.79 398,094 17,942 2,092,913
Total Inferred  872,619 140 2.74 - - 3,932,994 76,901 10,344,645

1Mineral Resource Estimates use an effective date of July 31, 2019 and October 31, 2019 for San Ignacio and Guanajuato mines respectively, and used a metal price outlook of US$15.80/oz silver and US$1,290/oz gold. Mineral Resource Estimates for El Horcon use an effective date of August 31, 2016 and used a metal price outlook of US$18.00/oz silver, US$1,300/oz gold, and US$0.80/lb lead.

Notes for San Ignacio mine Mineral Resource Estimate:

  1. Ven bulk density of 2.64t/m³.
  2. Measured, Indicated and Inferred Mineral Resources are reported at a full cost cut-off Net Smelter Return (NSR) of US$100/tonne.
  3. Totals may not agree due to rounding.
  4. Grades in metric units and contained silver and gold in troy ounces.
  5. Minimum true width 0.5m.
  6. Mineral Resources are estimated using metal prices of US$15.80/oz Ag and US$1,290/oz Au (based on 3 year back averages); and metallurgical recoveries of 88% Ag, 87% Au.
  7. 2019 Mineral Resources Ag eq oz were calculauted using 80:1 Ag:Au ratio. The ratios are refelctive of average metal prices for 2019.

Notes for Guanajuato mine Mineral Resource Estimate:

  1. Cut-offs are based on the marginal operating costs per mining area being US$113/tonne for Cata, US$75/tonne for Santa Margarita / San Cayetano, US$77/tonne for Los Pozos, US$124/tonne for Guanajuatito, US$60/tonne for Promontorio, and US$197/tonne for Valenciana.
  2. Block model grades converted to US$/t value using process plant recoveries of 88% Ag, 87% Au, and net smelter terms negotiated for pyrite concentrates.
  3. Rock Density for all veins is 2.68t/m³.
  4. Totals may not agree due to rounding.
  5. Grades in metric units.
  6. Contained silver and gold in troy ounces.
  7. Minimum true width 1.0m.
  8. Ag:Au ratio of 80:1 was used for Ag eq (oz)

Notes for El Horcón Mineral Resource Estimate:

  1. US$110 per tonne Cut-off, considering plant recoveries of %Ag, %Au, %Pb, and net smelter terms typical for Pb concentrates.
  2. Rock Density for all veins for Diamantillo is 2.77t/m³, San Guillermo 2.78t/m³, Diamantillo HW is 2.62t/m³, Natividad 2.57t/m³.
  3. Totals may not agree due to rounding.
  4. Grades in metric units.
  5. Contained silver and gold in troy ounces.
  6. Minimum true width 1.5m
  7. Metal Prices US$18.00/oz silver, US$1,300/oz gold, and US$0.80/lb lead.
  8. Silver equivalent calculations for El Horcón include gold and lead content but not zinc, as the zinc would not be recovered in the Guanajuato plant.
  9. Report effective date of August 31, 2016.

Technical information for the Guanajuato and San Ignacio mines has been reviewed and approved by the Company’s employees Robert F. Brown, P. Eng., and Mohammad Nourpour, P. Geo., who are the Qualified Persons for GMC under the meaning of NI 43-101. Aspects relating to mining and metallurgy are overseen by Neil Hepworth, C. Eng. and COO for Great Panther.

NI 43-101 Technical Report on the GMC, Guanajuato Mine

Guanajuato, Mexico   |   October 31, 2019

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NI 43-101 Technical Report on the GMC, San Ignacio Mine

Guanajuato, Mexico   |   July 31, 2019

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