Mining Intelligence and News
Chile

Maricunga (Refugio) Mine

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Overview

Mine TypeOpen Pit
StatusClosing / Closed
Commodities
  • Gold
Mining Method
  • Truck & Shovel / Loader
Production Start... Lock
SnapshotKinross has been reporting since 2016 on sanctions and legal cases brought by Chilean authorities against the Maricunga mine (“CMM”), for alleged damages to wetlands at Pantanillo and Valle Ancho. In January 2022, the Supreme Court annulled previous rulings by the Environmental Tribunal in the two cases against the Company and ordered that the case be sent back to the Environmental Tribunal. At the same time, the Company is pursuing settlement discussions with the relevant authorities and developed a proposal for recovery of the area. Comments were received from the authorities in early 2023 and a field visit organized by the Chilean State Defense Council (“CDE”) occurred in September 2023 with the participation of additional Government agencies. In Q4 2023, CMM received all agency comments and incorporated them into the draft recovery plan. CMM submitted the updated draft of the recovery plan to the CDE on January 15, 2024.

Owners

SourceSource
CompanyInterestOwnership
Kinross Gold Corp. 100 % Indirect
Compania Minera Maricunga S.A. (operator) 100 % Direct
The Maricunga heap leach mine, formerly known as the Refugio mine, is owned and operated by Kinross’ wholly-owned subsidiary Compania Minera Maricunga S.A. (CMM).

Deposit type

  • Porphyry
  • Breccia pipe / Stockwork

Summary:

Gold mineralization at Maricunga has been interpreted to be porphyry style gold systems.

The Verde and Pancho gold deposits at Maricunga occur in the Maricunga Gold Belt of the high Andes in northern Chile.

The Maricunga volcanic-intrusive complex is exposed over an area of 12 km2 and consists of andesitic to dacitic domes, flows, and breccias that are intruded by subvolcanic porphyries and breccias (Muntean 1998).

At Verde West, gold mineralization is centered about an elliptical porphyry plug measuring 175 by 100 m and oriented at N30°W. At Verde East, the porphyry plug measures 130 by 80 m and is oriented at N35°E. The porphyries occur within a sequence of intermediate tuffs, porphyries and breccias that are the host rocks to the gold mineralization. Lithological interpretation at Verde has identified six major lithologic units. These are:

• Post mineral intrusives (barren);
• Mineralized post mineral intrusives;
• Verde breccia;
• Dacite porphyry;
• Dacite tuffs;
• Laguna tuff (barren).

The most favourable ore hosts are the Verde Breccia and Dacite Porphyry units. The dacite porphyry is a volcanic to hypabyssal intrusive rock with 20% to 40% plagioclase phenocrysts in a fine-grained matrix. It contains phenocrysts of biotite, hornblende, and sparse quartz. The unit is the best host for stockwork veining, with some portions containing up to 20% quartz-magnetite ± pyrite veinlets.

The Verde Breccia consists of intrusive breccia and/or volcanic tuff breccia. Its geometry suggests an intrusive origin. The unit consists of breccia with angular to rounded clasts, generally matrix supported. The breccia is generally green to greenish gray, which is one of the diagnostic features of the unit. The color of the rock is largely due to chlorite and occasionally epidote. The fragments range from 2 mm to greater than 2 meters in size. Locally the unit is mostly matrix-sized material with only sparse clasts. Clasts in the unit are generally monolithic volcanic fragments, which are often porphyritic with white plagioclase laths up to 5 mm in length. The unoxidized rock typically contains 0.5 to 1% pyrite. Quartz-magnetite veinlets are common in the mineralized portions of the unit. In places, the breccia is cut by fine-grained matrix material that forms clastic-like dikes. These are generally > 2 cm in width. They may have been formed as “fluidized” material injected into fractures at the time of the formation of the unit.

Gold mineralization at Verde is interpreted to be the result of the fracturing and concentration of fluids in the carapace of an intrusive plug or stock. Gold is closely associated with quartz, magnetite, calcite, and garnet stockworks. Approximately 80% of the stockwork veins are generally dark grey in color, finely banded, with magnetite. The remaining 20% are principally white quartz veins. Gold mineralization is postulated to have resulted from at least 2 phases of mineralization, the first is a lower grade phase associated with copper and probably the porphyry emplacement event. The second phase is a higher-grade gold only event possibly associated with the structurally emplaced veinlet swarms and northwest trending sheeted veinlet zones more evident in Verde East. Verde East and Verde West cover an area of 1.4 km in length by 700 km in width. Drilling has identified gold mineralization to a depth of a 600 m.

The porphyritic diorite intrusives and intrusive breccias are the main hosts for mineralized veins. Mineralization is also hosted by the volcanic rocks. The mineralization is commonly related to the various geologic features listed below:

• directly associated with the presence of B, A and T veinlets;
• in silicified zones, normally micro-granular and a dark grey color, with or without the
presence of magnetite;
• associated with intrusive breccias;
• in contact zones such as the contact between the intrusive breccia with the volcanic breccia or the contact between the intrusive breccia and the diorite porphyry.

In the porphyry the veins are present in stockwork or sheeted veins. They are generally subvertical and have a strong, preferred north-westerly strike. The northwest structural control is evident not only at outcrop scale but is also reflected in the northwest alignment of intrusives and the three centers of mineralization in the district, Verde, Pancho and Guanaco. The mineralization outlined to date at Pancho comprises an area of 800 m by 700 m. Gold porphyry mineralization was identified in drilling at depths exceeding 600 m.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

Milling equipment has not been reported.

Processing

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Production

As a result of the suspension of mining and crushing activities at Maricunga, there was no new ore mined and processed in both 2020 and 2019. Production continued through 2019 as ounces continued to be recovered from the heap leach pads until the fourth quarter of 2019 when production activities transitioned to care and maintenance.
CommodityUnits202020192018201720162015
All production numbers are expressed as metal in doré.

Operational metrics

Metrics20162015
Ore tonnes mined 6,059 kt12,261 kt
Tonnes processed 6,508 kt12,790 kt
Daily milling capacity 48,000 kt
Annual milling capacity

Production Costs

CommodityUnits2020201920182017
Cash costs (sold) Gold Equivalent USD  ....  Subscribe 720 / oz   730 / oz   482 / oz  

Financials

Units2020201920182017
Capital expenditures M USD 1.5  
Revenue M USD  ....  Subscribe 61.2   113.6   52  
Operating Income M USD  ....  Subscribe 10.9   45.1   21.3  
Gross profit M USD 28   43.9   27.5  

Heavy Mobile Equipment

Fleet data has not been reported.

Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Jun 9, 2023
....................... Subscription required ....................... Subscription required Subscription required Jun 9, 2023
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Aerial view:

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