Cap-Oeste Mine

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Mine TypeOpen Pit & Underground
StageResidual leach
  • Gold
  • Silver
Mining Method
  • Truck & Shovel / Loader
  • Longhole open stoping
Production Start... Lock
ShapshotCap-Oeste has been on care and maintenance since February 2019 though residual leaching continues.

On March 9, 2021, the Patagonia Gold announced that it had obtained definitive permits for the development of the Cap-Oeste Property.

The Patagonia Gold has initiated a pre-feasibility study to assess the potential technical and economic extraction of mineral resources. The Patagonia Gold is now focused on evaluating the development of these mineral resources by underground mining.


FOMICRUZ 4.7 % Indirect
Patagonia Gold Plc. 95.3 % Indirect
Patagonia Gold S.A (operator) 100 % Direct
Ownership Tree

Deposit type

  • Epithermal
  • Vein / narrow vein
  • Breccia pipe / Stockwork


Gold and silver mineralisation at Cap Oeste is hosted by the northwest trending Cap Oeste Breccia Fault, which dips 75° to 90° to the southwest.

The drilling to date has defined a high-grade shoot, approximately 130 m long and 12 m to 15 m wide, situated in the interpreted southeast extension of the Bonanza Fault. The high-grade ore shoot pitches steeply to the west north-west over an approximate 120 m vertical interval, extending from 135 m to 255 m vertically below surface as currently defined by the drilling to date. Mapping, trench sampling and drilling has confirmed that the high-grade shoot is overlain by a broader (e.g. 20 m thick) zone of more diffuse lower grade, high Ag/Au ratio mineralisation and trace element anomalism.

The highest-grade Au-Ag mineralisation is hosted by a distinctive suite of sinuous to weakly bifurcating breccia, comprising argillic altered characteristically rounded fragments of volcanic host rock in a sulphide rich milled breccia matrix of fine-grained grey quartz, illite, and carbonaceous material. Precious metals occur as native metal, alloys and sulphides, in close association with base metal sulphides, pyrite, and arsenopyrite. These zones of very high-grade Au-Ag mineralisation are referred to by PGD as ‘hypogene’ mineralisation, or more commonly ‘COSE’ style mineralisation, as a reference to the nearby COSE au-ag mineralisation style to the south-east of Cap Oeste.

PGD geologists have defined several broadly defined successive types of mineralisation at Cap Oeste CAM (2012). The individual types are defined according to their respective locations in relation to the Bonanza Fault or Esperanza Faults. Cube has labelled two main zones of mineralisation based on the 3D interpretation as the Bonanza Fault (“BZ”) breccia mineralisation and the Esperanza Fault (“EZ”) quartz vein style mineralisation.

Deposit Types
Exploration by PGD throughout the El Tranquilo Block is focused principally on discovery and delineation of low sulfidation, Au-Ag epithermal mineralisation of the type well documented throughout the Deseado Massif [e.g. White and Hedenquist (1990), Corbett, G.J. (2001) and Sillito, R.H. (1993)]. Mineralisation typically comprises banded fissure veins and local vein/breccias characterised by high Au and Ag contents and ratios of Au:Ag generally greater than 1:10. Mineralised veins and breccias consist of quartz (coliform, banded, and chalcedonic morphologies), adularia, bladed carbonate (often replaced by quartz), and dark sulphidic material termed ginguro (fine grained electrum or Ag sulphosalts banded with quartz). Discrete vein deposits, such as at Cap Oeste, develop where mineralising hydrothermal fluids are focused into dilatant structures, producing ore shoots which host the highest precious metal grades. Low sulfidation mineralisation can also develop where mineralising fluids flood permeable lithologies to generate large tonnage, low grade disseminated deposits (e.g. Round Mountain, Nevada; McDonald Meadows, Montana).

Studies of alteration patterns and fluid inclusion data demonstrate that precious metal precipitation generally occurs between 180° to 240° Celsius, corresponding to depths 150 m to 450 m below the paleosurface (Figure 8-1) Deposits often exhibit a top to bottom vertical zonation:
• Precious-metals-poor, paleosurface, sinter (Hg-As-Sb);
• Au-Ag-rich, base metal poor “bonanza zone” (Au-Ag-As-Sb-Hg); and
• Ag-rich, base metal zone (Ag-Pb-Zn-Cu).

Alteration is controlled by the temperature and pH of the circulating hydrothermal fluids and its distribution therefore can be spatially zoned. Alteration minerals that occur proximal to mineralisation include illite, sericite, calcite and adularia, whereas smectite and chlorite typically occur in a more distal setting. Additional variants include pervasive silicification of wall rock as envelopes to quartz veins and breccias, and advanced argillic alteration (alunite, jarosite, kaolinite, vuggy silica) in steam heated horizons at higher structural levels.

Mineralisation at Cap Oeste is also assigned to the low sulfidation type, based on the presence of finegrained replacement quartz and adularia, widespread illite alteration, bladed textures indicative of hydrothermal boiling, and a mineral assemblage dominated by marcasite, arsenopyrite and silverbearing sulphosalts. The presence of anomalous copper and molybdenum associated with higher grade Au-Ag mineralisation suggests a component of magmatic-derived fluid.

The Cap Oeste deposit occurs predominantly as hydrothermal breccia, in combination with replacement, veinlet and disseminated styles of mineralisation, rather than as one or more discrete quartz veins. This is somewhat atypical for the Deseado Massif deposits, perhaps reflecting a lack of open space during hydrothermal fluid flow.



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Mining Methods


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Crushers and Mills

Milling equipment has not been reported.



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CommodityUnits2022202120202019201820172016LOM (Projected)
Gold oz  ....  Subscribe  ....  Subscribe  ....  Subscribe7,7962,908
Silver oz  ....  Subscribe  ....  Subscribe  ....  Subscribe237,7278,864
Gold Equivalent oz  ....  Subscribe  ....  Subscribe  ....  Subscribe10,58542,90620,0883,064186,800
All production numbers are expressed as metal in doré.

Operational metrics

Total tonnes mined 364,618 t750,000 t
Tonnes processed 220,000 t336,000 t
Waste 2.16 Mt

Production Costs

Cash costs Gold Equivalent USD  ....  Subscribe  ....  Subscribe 573 / oz  
Total cash costs Gold Equivalent USD  ....  Subscribe


Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 14.9   48.1   23.9  
Gross profit M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 3.1   5.1   9.7  
Pre-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 2.5   2.7   8  
After-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 2.5   2.7   8  

Heavy Mobile Equipment

Fleet data has not been reported.


Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Sep 29, 2023
....................... Subscription required ....................... Subscription required Subscription required Sep 29, 2023


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