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Mexico

Cozamin Mine

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Overview

Mine TypeUnderground
StatusActive
Commodities
  • Copper
  • Silver
  • Zinc
  • Lead
Mining Method
  • Longhole open stoping
  • Longitudinal open stoping
  • Transverse open stoping
  • Mechanized Cut & Fill
Backfill type ... Lock
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SnapshotCozamin Mine concentrate production is primarily copper with significant by-product silver, lesser amounts of by-product zinc and lead concentrate and small amounts of by-product gold credits.

Construction of the new paste backfill plant was completed late in 2022 and ramped up in 2023. Approximately half of the filtered tailings are combined with cement to form a paste and pumped underground to be used as mine backfill, allowing for increased copper ore extraction.

Owners

SourceSource
CompanyInterestOwnership
Capstone Gold, S.A. De C.V. (operator) 100 % Direct
Capstone Copper Corp. 100 % Indirect
Capstone owns 100% of Cozamin through its subsidiaries Capstone Gold S.A. de C.V. (Capstone Gold; 99.9% ownership) and Capstone Mexico Mining Corp. (0.01% ownership).

On March 23, 2022, Capstone Mining and Mantos Copper completed the business combination announced on November 30th, 2021. The resulting company was renamed Capstone Copper Corp. (“Capstone Copper”, or “Capstone”). Capstone’s shares continue to be listed on the Toronto Stock Exchange under the ticker symbol “CS”.

Contractors

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Deposit type

  • Vein / narrow vein
  • Epithermal

Summary:

Deposit Types
All mineralization at Cozamin occurs in veins, and fracture-controlled systems of veinlets. Currently mined mineralization at Cozamin is best described as an intermediate sulphidation system. The copper-rich intermediate sulphidation mineralization is an early phase that is enveloped, overprinted or brecciated by zinc-rich intermediate sulphidation mineralization. The copper veins are inferred to be higher temperature, have significantly fewer vugs and can be massive pyrrhotite-pyrite-chalcopyrite with little gangue. Zinc-rich veins also tend to be sulphide rich, like the copper-rich ones, but with slightly more gangue. Well-banded quartz, or quartzcarbonate veins are inferred to be lower temperature and best classified as low sulphidation. They often have open space filling textures with quartz druse vug linings and typically gold and silver rich with lesser base metals and are generally not being mined today, but were historically important.

This transition from intermediate sulphidation copper-dominant mineralization to intermediate sulphidation zinc-dominant mineralization is thought to be the result of an evolving, telescoped hydrothermal system. Blocks or fragments of massive chalcopyrite-pyrite-pyrrhotite mineralization enveloped by zinc-dominant mineralization are observed in drill core and in mine workings. This telescoping system is closely associated with the district’s largest center of rhyolite flow domes which may be the shallow expression of a hidden, inferred buried felsic stock.

Mineralization
Cozamin’s dominant mineralized vein systems include the MNV and the MNFWZ. On surface, the MNV was mapped for 5.5 km across the property. It strikes approximately EW and dips on average at 60° to the N. There are several shafts that provide access to the historical workings at Cozamin. The largest historical mined area is San Roberto with a strike length of 1.4 km, and the second largest mined area is San Rafael mine with a strike length of 0.5 km. Mineralization peripheral to these workings was the principal target of Capstone’s early exploration programs at Cozamin. The MNV system average thickness is five meters. It has been drill tested to an approximate depth of 1,500m, remaining open at depth. The MNFWZ is not exposed at surface, however based on drill testing to an approximate depth of 1,450m, it strikes approximately 145° over a length of more than 2.2 km and dips on average 54° to the NE. Thickness of mineralization in the MNFWZ areas most prospective for exploration varies from 0.5m to 15m true width. MNFWZ mineralization remains open locally up-dip, down-dip, and along strike to the east and west.

The MNV system occupies a system of anastomosing faults. The mineralized bodies within the Mala Noche Fault System appear to be strongest where the individual faults coalesce into a single fault zone. Results from exploration and mine development to date indicate that some of the strongest mineralization in the San Roberto mine on the MNV system plunges to the west at approximately -50° within the vein. Post mineralization offsets of the MNV are minimal and occur along high angle, normal faults that strike northeast. The MNFWZ comprises multiple veins in close spatial association with rhyolite dikes and locally cross-cut the intrusions themselves. The strongest mineralization at the MNFWZ plunges to the northwest at approximately -10° within the vein. The relative age of the copper mineralization ranges from contemporaneous with to perhaps slightly post the rhyolite magmatism. Similar to the MNV, post mineralization offsets at the MNFWZ are minimal and occur along high angle normal faults.

Mineralization in the MNV at Cozamin appears to have been episodic. Intermediate sulphidation pyrite-pyrrhotite-chalcopyrite dominant mineralization is enveloped, overprinted or brecciated by younger sphalerite dominant intermediate sulphidation epithermal alteration and mineralization in a telescoped, intrusive related hydrothermal system. Well-banded quartz, or quartz-carbonate veins, best classified as low sulphidation are also observed but are generally volumetrically insignificant in the area of the mine. These veins have open space filling textures with quartz druse vug linings. The MNV in the San Roberto mine workings shows contained sulphides to occur as disseminations, bands and masses. The San Roberto area hosts both the copper dominant and zinc dominant epithermal events, whereas the San Rafael area is only associated with the zinc dominant epithermal event. Both events are also present at MNFWZ. Conclusions about mineralization styles are based on observations in drill core and the exposure of the coppersilver phase of mineralization in mine workings, however a large portion of the upper parts of the mine are not accessible.

Pyrite is the dominant vein sulphide and typically comprises approximately 15% of the MNV in the San Roberto mine. It occurs as fine disseminations and veinlets, coarse crystalline replacements, and pseudomorphs of epithermal textured carbonate minerals and possible barite. Arsenopyrite locally occurs as minor, microscopic inclusions in pyrite. Pyrite content in the MNFWZ veins is typically greater than 20%.

Pyrrhotite is the second most common sulphide mineral but is present only in the intermediate and deeper levels of the San Roberto mine, and the up-dip portion of the MNFWZ. It occurs as replacement masses, pseudomorphs of platy masses and acicular replacements probably after amphibole. Pyrrhotite commonly occurs as an envelope to, or intermixed with, strong chalcopyrite mineralization. Pyrrhotite ranges from monoclinic to hexagonal, or a combination of these polytypes.

Chalcopyrite is the only copper sulphide recognized visually at Cozamin. Like pyrrhotite, it is more common at the intermediate and deeper levels of the mine. It occurs as disseminations, veinlets and replacement masses. These masses appear to be fractured and brecciated at intermediate levels in the mine. Mineralization at the MNFWZ in the copper dominant veins is chalcopyrite dominant in contrast to the polymetallic nature of the main MNV.

Sphalerite is the most common economic sulphide in the zinc-dominant areas of MNFWZ, such as Vein 10-southeast, and in MNV’s San Roberto-Zinc zone and San Rafael. Most of the sphalerite is marmatitic. It occurs as disseminations and coarse crystalline masses and is commonly marginal to the chalcopyrite-dominant portion of the vein. Sphalerite is locally present in the MNFWZ copper dominant veins, shifting to the dominant sulphide in the zinc dominant veins.

Franklinite, a zinc oxide in the spinel group of minerals, accounts for some of the zinc mineralization in the MNV. Recovery of zinc is lower in areas of franklinite mineralization.

Galena is less common than sphalerite but is generally associated with it. Where it is abundant, it occurs as coarse crystalline replacement masses. Both coarse and fine crystalline masses of galena are argentiferous.

Argentite is the most common silver mineral. It has been identified microscopically occurring as inclusions in chalcopyrite and pyrite. Assays indicate that silver is also probably present in sphalerite and galena. Bismuth and silver selenides occur as inclusions predominantly in chalcopyrite and pyrite.

At MNV and MNFWZ, moderate propylitic wall rock alteration is generally limited to 3 m into the hangingwall and footwall. The main gangue minerals are quartz and calcite, and in some cases rhodochrosite, gypsum, barite, or ilvaite. The quartz occurs as coarse-grained druse crystalline masses, and cross-cutting quartz veinlets.

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

CommodityProductUnits2024202320222021202020192018201720162015
Copper Payable metal M lbs  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe3435353033
Copper Metal in concentrate M lbs  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe3636373235
Silver Metal in concentrate koz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe1,3661,1641,0001,0011,287
Zinc Metal in concentrate M lbs  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe18159.39.213
Copper Concentrate kt  ....  Subscribe  ....  Subscribe  ....  Subscribe6163615461
Zinc Concentrate kt  ....  Subscribe  ....  Subscribe  ....  Subscribe17148.98.912
Lead Concentrate kt  ....  Subscribe  ....  Subscribe2.42.30.080.21.2
^ Guidance / Forecast.

Operational metrics

Metrics202320222021202020192018201720162015
Daily milling rate  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe3,140 t2,702 t2,499 t2,736 t2,958 t
Daily milling capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Ore tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe1,143 kt989 kt912 kt996 kt1,079 kt
Tonnes milled  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe1,146 kt986 kt912 kt1,001 kt1,080 kt

Production Costs

CommodityUnits20242023202220212020201920182017
Credits (by-product) Copper USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe -1.07 / lb   -0.94 / lb   -0.5 / lb  
All-in sustaining costs (AISC) Copper USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 1.84 / lb **   1.5 / lb **   1.9 / lb **  
C1 cash costs Copper USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 0.9 / lb **   0.75 / lb **   1.16 / lb **  
All-in costs Copper USD 1.9 / lb **  
^ Guidance / Forecast.
** Net of By-Product.

Operating Costs

Currency202120202019201820172016
Total operating costs ($/t milled) USD 43.9  42.7  48.5  49.4  50.5  41.7  

Financials

Units20242023202220212020201920182017
Capital expenditures (planned) M USD  ....  Subscribe
Sustaining costs M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Capital expenditures M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 30.6   20.1   18.1  
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 118.4   121.2   108.4  
Operating Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 29.8   39.7   39.5  
Pre-tax Income M USD  ....  Subscribe  ....  Subscribe
After-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 18.3   24.4   28.2  
EBIT M USD  ....  Subscribe  ....  Subscribe 27.8   39.8   39.2  
EBITDA M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe

Heavy Mobile Equipment

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Personnel

Mine Management

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Aerial view:

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