Mexico

Bolanitos Mine

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Overview

Mine TypeUnderground
Commodities
  • Silver
  • Gold
Mining Method
  • Cut & Fill
  • Longhole open stoping
  • Unconsolidated rockfill
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Mine Life2025
ShapshotBolanitos mine is an Underground gold mine with exploration upside and nearby acquisition opportunities to provide future growth.

Currently, Endeavour is mining three orebodies at Bolañitos: Lucero, La Luz and San Miguel.

Owners

SourceSource
CompanyInterestOwnership
Endeavour Silver Corp. 100 % Indirect
Endeavour Silver Corp. controls the Bolanitos Project through its 100% owned subsidiary, Minera Bolañitos SA. de CV.

Contractors

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Deposit type

  • Vein / narrow vein
  • Epithermal

Summary:

Local Geology
Epithermal systems form near the surface, usually in association with hot springs, and to depths on the order of a few hundred meters. Hydrothermal processes are driven by remnant heat from volcanic activity. Circulating thermal waters rising through fissures eventually reach a level where the hydrostatic pressure is low enough to allow boiling to occur. This can limit the vertical extent of the mineralization, as the boiling and deposition of minerals is confined to a relatively narrow range of thermal and hydrostatic conditions. In many cases, however, repeated healing and reopening of host structures can occur, imparting cyclical vertical movement of the boiling zone and resulting in mineralization that spans a much broader range of elevation.

Local Geology Of the geological formations associated with the Guanajuato district only the Esperanza and La Luz Formations occur in the Bolañitos mine area with mineralization residing primarily within the La Luz Formation. Mineralization is known to dissipate at the contact with the Esperanza Formation.

The vein dips from 35° to 55º to the southwest with measured displacement of around 1,200m near the Las Torres mine and 1,700 m near La Valenciana mine. The most productive veins at Bolañitos strike parallel to the Veta Madre system.

Bolañitos mineralization is directly related to faulting. Mineralization occurs as open-space fillings in fracture zones or impregnations in locally porous wall rock. Veins which formed in relatively open spaces are the main targets for mining.

There are 21 veins within the Bolañitos mine area that are included in the mineral resource estimate. These mineralized veins are known to occur from an elevation of 2300 m down to an elevation of 1900 m.

Deposit Type
The Guanajuato silver-gold district is characterized by classic, high grade silver-gold, epithermal vein deposits with low sulfidation mineralization and adularia-sericite alteration. The Guanajuato veins are typical of most epithermal silver-gold vein deposits in Mexico with respect to the volcanic or sedimentary host rocks and the paragenesis and tenor of mineralization.

Epithermal systems form near the surface, usually in association with hot springs, and to depths on the order of a few hundred meters. Hydrothermal processes are driven by remnant heat from volcanic activity. Circulating thermal waters rising through fissures eventually reach a level where the hydrostatic pressure is low enough to allow boiling to occur. This can limit the vertical extent of the mineralization, as the boiling and deposition of minerals is confined to a relatively narrow range of thermal and hydrostatic conditions. In many cases, however, repeated healing and reopening of host structures can occur, imparting cyclical vertical movement of the boiling zone and resulting in mineralization that spans a much broader range of elevation.

Low-sulfidation epithermal veins in Mexico typically have a well-defined, sub-horizontal ore horizon about 300 m to 500 m in vertical extent, where high grade ore shoots have been deposited by boiling hydrothermal fluids. The minimum and maximum elevations of the mineralized horizons at the Bolañitos mine have not yet been established precisely, but historic and current production spans an elevation range from 1900 to 2300 m.

Mineralization
Mineralized veins at Bolañitos consist of the classic banded and brecciated epithermal variety. Silver occurs primarily in dark sulfide-rich bands within the veins, with little mineralization within the wall rocks. The major metallic minerals reported include pyrite, argentite, electrum and ruby silver, as well as some galena and sphalerite, generally deeper in the veins. Mineralization is generally associated with phyllic (sericite) and silicification alteration which forms haloes around the mineralizing structures. The vein textures are attributed to the brittle fracturing-healing cycle of the fault-hosted veins during and/or after faulting.

Economic concentrations of precious metals are present in “shoots” distributed vertically and laterally between non-mineralized segments of the veins. Overall, the style of mineralization is pinch-and-swell with some flexures resulting in closures and others generating wide sigmoidal breccia zones.

The silver-rich veins of Bolañitos contain quartz, adularia, pyrite, acanthite, naumannite, arsenopyrite and native gold. Native silver is widespread in small amounts. Much of the native silver is assumed to be supergene. Silver sulfosalts (pyrargyrite and polybasite) are commonly found at depth.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

CommodityProductUnits2023202220212020201920182017
Silver Metal in concentrate koz 000000000000000000976934
Gold Metal in concentrate koz 0000000000002127
Silver Equivalent Payable metal koz 0000000000000000000000002,5602,952
Silver Payable metal koz 000000000000947897
Gold Payable metal koz 000000002126
^ Guidance / Forecast.

Operational metrics

Metrics202320222021202020192018
Daily processing rate 0000000000000000001,203 t
Daily processing capacity 00000000000000001,600 t
Waste 000000000000
Tonnes processed 000000000000000000000000439,005 t
Ore tonnes mined 000000000000
^ Guidance / Forecast.

Production Costs

CommodityUnits202220212020201920182017
Total cash costs Silver USD 000 00 00 12.9 / oz   10.5 / oz   10.3 / oz  
Total cash costs Gold USD 0000 0000 0000 1,124 / oz   849 / oz   767 / oz  
Total cash costs Silver USD 0000000 00000000 00000000 6.72 / oz   2.14 / oz   -4 / oz  
All-in sustaining costs (AISC) Silver USD 000000 0000000 0000000 25.1 / oz   9 / oz   1.62 / oz  
Net of By-Product.

Operating Costs

Currency2022202120202019201820172016
Direct operating costs ($/t milled) USD 94.4  79.4  70.1  77.3  64.2  67.7  57.1  

Financials

Units2023202220212020201920182017
Capital expenditures (planned) M USD  ....  Subscribe
Sustaining costs M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 3.5   1.6  
Capital expenditures M USD  ....  Subscribe
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 39.8   48.4  
Pre-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 12.5   17.5  
After-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 11.5   15  

Heavy Mobile Equipment

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Personnel

Mine Management

Source Source
Job TitleNamePhoneProfileRef. Date
....................... Subscription required ....................... Subscription required ........... Subscription required Subscription required Aug 1, 2023
....................... Subscription required ....................... Subscription required Subscription required Jul 28, 2023
....................... Subscription required ....................... Subscription required Subscription required Jul 28, 2023

EmployeesContractorsTotal WorkforceYear
Subscription required Subscription required Subscription required 2022
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Aerial view:

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