El Cubo Complex

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Mine TypeUnderground
  • Silver
  • Gold
Mining Method
  • Mechanized Cut & Fill
  • Resue mining
  • Longhole open stoping
Backfill type ... Lock
Mine Life... Lock
SnapshotGuanajuato Silver operates the combined El Cubo and El Pingüico properties - El Cubo Complex.

El Cubo is approximately 5 kilometers from El Pingüico. Both properties utilize El Cubo's existing mill.

Guanajuato Silver is exploring, developing, and processing mineralized material from the El Cubo property and other sources. At El Pingüico, only material from the surface stockpile has been hauled to the El Cubo concentrator for processing.
Related AssetEl Cubo - El Pinguico Project


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.



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Deposit type

  • Vein / narrow vein
  • Epithermal


Deposit Type
The Guanajuato Mining District is a world-class, high-grade, silver-gold, epithermal vein system with low sulfidation and adularia-sericite alteration.

Epithermal systems form relatively near the surface, ranging from hot spring style gold and gold-silver mineralization developed in sinter terraces and shallow bedrock with deeper hydrothermal feeder zones to vein deposits and hanging wall splits at depths of several hundred meters. The hydrothermal solutions are driven by heat from volcanic activity. The hot circulating hydrothermal waters rise up through fissures with pressures building up until the hydrostatic pressure is released (sometimes explosively) allowing solutions to boil and precipitate the metallic minerals. Typically, this is a cyclical or recurring event as the fissures repeatedly get plugged and pressures build up until fracturing once again releases the hydrostatic pressure. The typical banding nature of the veins represents the cyclical pressure buildup, release by fracturing, boiling, and precipitation of minerals multiples of times until the system is finally exhausted. These multiple events allow the range of economic mineralization to expand to a broader vertical range.

Low sulfidation epithermal veins in the region typically have a well-developed, sub-horizontal ore horizon about 300 m to 500 meters in vertical extent where high grade vertical ore shoots develop during hydrothermal fluid boiling and mineral precipitation. In some districts, multiple sub-horizontal horizons develop. The minimum and maximum elevations of mineralized horizons at El Cubo have not yet been precisely defined, but historic production spans an elevation range from 1,850 meters to 2,650 meters, with known mineralization down to the 1,825 m elevation.

Silver and gold are commonly zoned in epithermal systems and mineralization at El Cubo is no exception. The gold to silver ratios range from 1:15-1:30 in the upper reaches of mineralization (typified by San Nicolas, Area 1) to 1:100- 1:150 at depths (typified by Peregrina, Area 4, and Dolores 2, Area 2).

Low sulfidation deposits are formed by the circulation of hydrothermal solutions that are near neutral in pH; thus, there is very little acidic alteration within the host rocks and no widespread pyritic haloes. The characteristic alteration assemblages include illite clay, sericite, and adularia along with silicification that are hosted within the veins or in the adjacent wall rocks. Adularia is a particularly important alteration mineral as it is a guide to economic mineralization. Amethyst is locally associated with gold and silver mineralization and calcite is a late stage mineral. The hydrothermal fluids travel along fissure/faults or other openings or can also travel through very porous rock types such as poorly welded ignimbrites or ash fall tuffs. Fluids that travel along fissure and faults develop into veins or vein breccia zones while fluids traveling along porous rock units tend to form disseminated deposits.

El Cubo mineralization is typical of the classic high-grade silver-gold, banded epithermal vein deposits with low sulfidation mineralization characterized by adularia-sericite-silica alteration. Silver occurs in dark sulfide-rich bands within the veins with little mineralization but 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 typical of these type 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).

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 sometimes 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-sulfidation epithermal deposits in Mexico, such as El Cubo and El Pinguico, commonly have a well-defined, subhorizontal zone where the hydrothermal fluids deposited gold and silver mineralization. Regionally, ore horizon thickness ranges from at least 300 m to greater than 500 m. High-grade ore occurs where the hydrothermal fluids boiled. Below the higher-grade silver gold mineralization, silver and gold values decrease but base metal values increase.

Phyllic alteration, as sericite and silicification, forms as haloes surrounding and adjacent to the silver-gold veins. Banding is due to periodic boiling events related to pressure releases during faulting of the brittle silicified host rocks. Amethyst is locally common, and calcite is commonly a late stage mineral.

Typical of this style of mineralization, economic concentrations of silver and gold occur in ore 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 Nicolas-Villalpando vein intersection. Other vein intersections of various named splays along the principal Villalpando vein also host bonanza silver-gold mineralization. Movement along the strike or dip direction of veins during the hydrothermal episodes causes wide sigmoidal breccia zones typified by pinch and swell mineralization.



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Mining Methods


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Crushers and Mills


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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.
Silver Metal in concentrate oz  ....  Subscribe  ....  Subscribe  ....  Subscribe1,086,8242,582,7401,919,1022,018,7452,288,145
Gold Metal in concentrate oz  ....  Subscribe  ....  Subscribe  ....  Subscribe10,46426,61621,35721,32728,634
Silver Equivalent Metal in concentrate oz  ....  Subscribe  ....  Subscribe  ....  Subscribe
Gold Payable metal oz 10,20025,98720,82320,65427,898

Operational metrics

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

Production Costs

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
All-in sustaining costs (AISC) Silver Equivalent USD  ....  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

UG mining costs ($/t milled) USD 35  33.9  42.6  
Direct operating costs ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Processing costs ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe
Total operating costs ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe


Sustaining costs M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 0.01   10   13.9  
Capital expenditures M USD  ....  Subscribe  ....  Subscribe
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 32.3   71.5   58.7  
Operating Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe
Pre-tax Income M USD  ....  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

Heavy Mobile Equipment


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Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required May 27, 2024
....................... Subscription required ....................... Subscription required Subscription required Dec 31, 2023
....................... Subscription required ....................... Subscription required Subscription required May 27, 2024
....................... Subscription required ....................... Subscription required Subscription required May 27, 2024

EmployeesContractorsTotal WorkforceYear
...... Subscription required ...... Subscription required ...... Subscription required 2019
...... Subscription required ...... Subscription required ...... Subscription required 2018
...... Subscription required ...... Subscription required ...... Subscription required 2017
...... Subscription required ...... Subscription required ...... Subscription required 2016
...... Subscription required ...... Subscription required ...... Subscription required 2015

Aerial view:


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