Mining Intelligence and News
Mexico

El Cubo Mine

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Summary

Mine TypeUnderground
StatusActive
Commodities
  • Silver
  • Gold
Mining Method
  • Mechanized Cut & Fill
  • Resue mining
  • Longhole open stoping
Backfill type ... Lock
Mine Life... Lock
SnapshotEl Cubo is a high-grade, underground precious metals mine that has been in operation for almost 200 years.

Following the acquisition of El Cubo in April 2021, GSilver completed refurbishment of the El Cubo Mill in September 2021 and commenced mining and processing of mineralized material from underground mining operations at El Cubo and surface stockpiled material at El Pingüico in October 2021.

El Cubo is an underground mining operation that includes the Villalpando and Santa Cecilia mines.

GSilver has mined surface stockpiled material from El Pingüico intermittently from October 2021 to the Effective Date of the 2025 El Cubo Report. Underground mining activities resumed at El Pingüico in July 2024, focusing on advancing Level 4.

The mineralized material produced from El Cubo and from surface stockpiles at El Pingüico is processed at the El Cubo processing plant.

Planned development by GSilver for 2025 will be focused on the Villalpando and Santa Cecilia mines.
Latest NewsGuanajuato Silver Reports Third Consecutive Quarter of Positive Mine Operating Income     April 28, 2025

Owners

SourceSource
CompanyInterestOwnership
Guanajuato Silver Company, Ltd. 100 % Indirect
Obras Mineras El Pinguico S.A. de C.V. (operator) 100 % Direct
El Cubo mine and mill (the "El Cubo Complex") is 100% owned of Guanajuato Silver.

Obras Mineras El Pinguico, S.A. de C.V., a subsidiary of Guanajuato Silver, holding all of the Company's interests in El Cubo and El Pinguico.

Obras Mineras El Pinguico S.A. de C.V. operates the El Cubo Mines Complex.

Contractors

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Deposit type

  • Vein / narrow vein
  • Epithermal

Summary:

Deposit Type
The Guanajuato Mining District in general is a high-grade, silver-gold, epithermal vein system with low sulphidation and adularia-sericite alteration. The primary deposit type of interest at the El Cubo and El Pingüico properties is low sulphidation epithermal silver-gold mineralization.

The mineral deposits in the Guanajuato region are classic fissure-hosted low sulphidation epithermal goldsilver-bearing quartz veins and stockwork. Low sulphidation epithermal mineralization are vein type deposits that form at shallow depth from dominantly meteoric fluids at low temperature with neutral to near neutral pH; thus, there is very little acidic alteration within the host rocks and no widespread pyritic haloes. Banded veins, drusy veins, crustiform veins, and lattice textures are common. Low sulphidation deposits typically have gold-silver mineralization, occasionally with banded adularia, sericite, rhodonite and rhodochrosite. Alteration in these systems is commonly sericite-illite proximal to mineralization, grading to illite-smectite and to chlorite ± epidote ± calcite alteration on the outer margins of the system. Mineralization in low sulphidation systems generally consists of Au ± Ag with minor Zn, Pb, Cu, Mo, As, Ab and Hg (Sillitoe and Hedenquist, 2003; Cooke and Hollings, 2017).

Mineralization of significance at the El Cubo and El Pingüico properties consists of veins containing significant silver- and gold-bearing metallic minerals including native silver, native gold, argentite or acanthite, electrum, pyrargyrite, polybasite, naumannite, and aguilarite. Accessory metallic minerals include pyrite, galena, sphalerite, and chalcopyrite. There is only little mineralization disseminated in the surrounding wall rocks. Gangue minerals include quartz (locally amethyst), calcite, adularia, and sericite. The veins are accompanied by hydrothermal alteration consisting of silicic, potassic (adularia+quartz), argillic, and phyllic alteration, and peripheral propylitic alteration. Mineral textures in this zone are typically fracture-filling, drusy and coliform masses.

Epithermal type precious metal deposits at El Cubo and El Pingüico are strongly vertically controlled. In the Guanajuato region there is commonly a well-defined, sub-horizontal zone where the hydrothermal fluids deposited gold and silver mineralization. Regionally, mineralized material horizon thickness ranges from at least 300 m to greater than 500 m. High-grade material occurs where the hydrothermal fluids boiled, and below the higher-grade silver-gold mineralization zones, the silver and gold grades tend to decrease but the base metal grades tend to increase. This creates a significant mineralogical zonation in the vein systems: the upper levels are argentite/acanthite + adularia + pyrite + electrum + calcite + quartz and the lower levels are chalcopyrite + galena + sphalerite + adularia + quartz + argentite/acanthite.

The low sulphidation epithermal system deposit characteristics encountered at the El Cubo and El Pingüico properties include: a quartz-adularia vein/breccia system; native silver; native gold; electrum; sulphides and silver-sulphides; sulfosalts; quartz and calcite; accessory pyrite, galena, sphalerite and chalcopyrite; fault and vein control; and a vertical extension of over 300 m, and up to ~825 m at El Cubo.

Mineralization
Mineralization at El Cubo consists of silver and gold occurring in several stratigraphic formations, with the La Bufa Formation, the Guanajuato Formation, and the Calderones Formation being the most important hosts.

Mineralization at El Cubo is typical of the classic high-grade silver-gold, banded epithermal vein deposits with alteration characterized by silica-adularia-sericite. Mineralization occurs as open-space fillings in fracture/fault zones or impregnations in locally porous wall rock. Weak stockwork style mineralization occurs in an historic open pit on the Dolores Vein in the vicinity of the El Tajo mill. The most productive veins are sub-parallel to the Veta Madre system as north-northwest striking veins and local stockwork style mineralization. Several transverse, northeast striking veins with high-grade gold mineralization such as the Marmajas, La Reina, and San Juan de Dios also occur. Mineralization is open-ended due to a lack of exploration drilling and development.

Silver occurs in dark sulphide-rich bands within the banded veins with significant alteration minerals in the surrounding wall rocks. Significant silver and gold bearing metallic minerals include argentite or acanthite (Ag2S), electrum (native Au/Ag), ruby silver sulfosalt minerals such as pyrargyrite (Ag3SbS3) and polybasite [(Ag/Cu)6(Sb,As)2S7][Ag9CuS4]), naumannite (Ag2S), native silver (Ag), native gold (Au), and aguilarite (Ag4SeS). Other metallic minerals include pyrite (FeS2), galena (PbS), sphalerite (ZnS), and chalcopyrite (CuFeS2). The silver sulfosalts are commonly found at depth while native silver is generally supergene and found in oxidized areas. As is typical of this type of systems, galena, sphalerite, and chalcopyrite are found deeper in the vein zones.

The silver-rich veins, such as Villalpando, contain quartz, adularia, pyrite, argentite (acanthite), naumannite, and native gold. Gold-rich veins, such as San Nicolas, contain quartz, pyrite, minor chalcopyrite and sphalerite, electrum, and aguilarite.

There is significant mineralogical zonation in the vein system. The upper levels are argentite (acanthite) + adularia + pyrite + electrum + calcite + quartz, and the lower levels are chalcopyrite + galena + sphalerite + adularia + quartz + argentite (acanthite). Boiling of the hydrothermal fluids in the upper levels locally produced bonanza silver and gold grade mineralization.

The gold:silver ratio in the more gold-rich veins typically ranges from 1:15 to 1:30. The gold:silver ratio in the silver-rich veins typically ranges from 1:60 to 1:150, and locally higher. The overall gold:silver ratio to date is 1:64. Metal zoning appears to be related, at least in part, to elevation. Ranges for gold:silver ratios at El Cubo vary from 1:10 to 1:20 in the upper mine levels, from 1:40 to 1:50 in the middle mine levels, and 1:100 to 1:150 at depth. These ratios could be of some importance in evaluating outcropping vein occurrences.

Low sulphidation epithermal deposits in Mexico, such as El Cubo and El Pingüico, commonly have a welldefined, sub-horizontal zone where the hydrothermal fluids deposited gold and silver mineralization. Regionally, mineralized material horizon thicknesses range from at least 300 m to greater than 500 m. High-grade material occurs where the hydrothermal fluids boiled. Below the higher-grade silver and gold mineralization zones, the silver and gold grades tend to decrease but the base metal grades tend to increase. Above the boiling zone, veins locally disappear or can be deflected into something as simple as a calcite vein with barely anomalous silver values or a fracture with argillic to phyllic alteration.

Typical of this style of mineralization, economic concentrations of silver and gold occur in mineralization shoots distributed vertically and laterally between barren or weakly mineralized portions of the veins. Bonanza grades may occur at the site of vein intersections, such as the nearly perpendicular San NicolasVillalpando vein intersection.

At the El Pingüico Mine, the major vein consists of both silver and gold in crumbling sugary to white crystalline quartz and calcite veins, within brecciated rhyolitic rock, and as a replacement in the altered rhyolite. Mineralization consists of native gold and silver, polybasite, pyrargyrite, tetrahedrite, marcasite, sphalerite, galena, pyrite, and chalcopyrite.

Reserves

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Mining Methods

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Heavy Mobile Equipment

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Comminution

Crushers and Mills

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Processing

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Commodity Production

The El Cubo Project was put on care and maintenance at the end of November 2019. Production of silver and gold concentrate from the El Cubo Mill re-commenced in October 2021.
CommodityProductUnits202420232022202120192018201720162015
Silver Metal in concentrate oz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe1,086,8242,582,7401,919,1022,018,7452,288,145
Gold Metal in concentrate oz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe10,46426,61621,35721,32728,634
Silver Equivalent Metal in concentrate oz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Silver Payable metal oz 1,051,3022,508,8501,842,3381,937,9952,195,379
Gold Payable metal oz 10,20025,98720,82320,65427,898

Operational metrics

Metrics202420232022202120192018201720162015
Daily ore mining rate  ....  Subscribe  ....  Subscribe  ....  Subscribe672 t1,427 t1,402 t1,599 t1,859 t
Daily processing rate  ....  Subscribe  ....  Subscribe  ....  Subscribe
Daily processing capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe1,500 t1,500 t1,500 t1,500 t2,200 t
Ore tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe245,418 t520,784 t511,836 t678,850 t
Tonnes processed  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe245,418 t520,784 t511,836 t583,772 t678,850 t
Annual processing capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe

Production Costs

CommodityUnits2024202320222021201920182017
Cash costs Silver USD 13.4 / oz   8.46 / oz   11.8 / oz  
Cash costs Gold USD 1,169 / oz   685 / oz   879 / oz  
Cash costs Silver USD 12 / oz **   2.87 / oz **   7.93 / oz **  
Total cash costs Silver Equivalent USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
All-in sustaining costs (AISC) Silver Equivalent USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
All-in sustaining costs (AISC) Silver USD 14.9 / oz **   8.86 / oz **   17.8 / oz **  
** Net of By-Product.

Operating Costs

Currency20242023202220212019201820172016
UG mining costs ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Direct operating costs ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Processing costs ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Total operating costs ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe

Mine Financials

Units20242023202220212020201920182017
Capital expenditures M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe
Sustaining costs M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 0.01   10   13.9  
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 32.3   71.5   58.7  
Operating Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Pre-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe -6.8   18.3   15.8  
After-tax Income M USD  ....  Subscribe  ....  Subscribe -7.8   18   15.4  
EBITDA M USD  ....  Subscribe
Operating Cash Flow M USD  ....  Subscribe

Personnel

Mine Management

Job TitleNameProfileRef. Date
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Workforce

EmployeesContractorsTotal WorkforceYear
...... Subscription required ...... Subscription required ...... Subscription required 2019
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...... Subscription required ...... Subscription required ...... Subscription required 2016
...... Subscription required ...... Subscription required ...... Subscription required 2015

Aerial view:

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