United States

Sunshine Mine

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Overview

Mine TypeUnderground
StageRestarting
Commodities
  • Silver
  • Copper
  • Lead
  • Zinc
  • Antimony
Mining Method
  • Underhand Cut & Fill
  • Overhand Cut & Fill
  • Longhole stoping
  • Cemented paste backfill
Mine Life27.85 years (as of Jan 1, 2020)
ShapshotSunshine Complex is composed of the Sunshine Mine and the Sunshine Refinery, located in Kellogg, Idaho. The Sunshine Mine property hosts one of the highest-grade, large primary silver deposits in the world.

The Sunshine Mine is an existing underground mine with more than 100 years of operating history. Mine operations have largely been suspended following a succession of bankruptcies by prior operators. The last activity at the mine was in 2008.

SSMRC's focus at the Sunshine Complex has been on identifying additional resources, maintaining permits, rehabilitating certain underground infrastructure, and acquiring the Sunshine Refinery and strategic land holdings to position the Sunshine Complex for its next luminous era as a global benchmark in silver mining and refining.

Owners

SourceSource
CompanyInterestOwnership
Sunshine Silver Mining & Refining Corp. 100 % Indirect
The Sunshine Mine Project is owned by Silver Opportunity Partners LLC (SOP), a wholly owned subsidiary of Sunshine Silver Mining & Refining Corporation (SSMRC), based in Denver, Colorado.

Contractors

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Deposit type

  • Vein / narrow vein

Summary:

The Sunshine Mine mineral deposits are narrow, high-grade vein deposits, which characteristically strike east-west and dip steeply (average 65°) to the south. The combination of faults, folds, fractures, and favorable host rocks created suitable conditions for mineral emplacement by silver-rich and silver-base metal veins.

The Sunshine Mine is one of the most productive mines in the more than 35 km long Coeur d’Alene Mining District. Mineralized deposits are localized in the 183 m thick St. Regis Formation and the underlying upper members of the 914 m thick Revett Formation. The contact between the formations is indistinct and locally picked as the bottom of the lower-most distinct purple-colored interval in the St. Regis. Rock types include argillite, siltite, sericitic quartzite, and vitreous quartzite. Siltite and argillite dominate in the St. Regis Formation; while in the Revett, lithologies are gray to pale greenish-gray siltite and quartzite. Changes in lithologies are noted on the scale from a few centimeters to a few meters. Detailed stratigraphy of the mine is poorly understood; geologic mapping by early workers focused on veins and alteration, facies changes, and subtleties between lithologies that complicate correlation and identification of rock units. The stratigraphic column in the mine is continually re-interpreted, and two apparent marker beds have been identified in the West Chance area. One of these argillaceous beds is thought to be a bentonite (ash tuff) unit and may assist in correlations throughout themine.

Faults
Four major west-northwest trending faults cut the mine area, and some have been mapped for several miles. The faults dip steeply to the south. The spatial relationship to the Osburn Fault suggests strike-slip movement, but studies of kinematics and rock fabrics in the mine show that most movement is dip-slip. The Polaris Fault has normal movement, but the Silver Syndicate, Chance, C, Chester, and Alhambra Faults have reverse movement. Offset is thought to be from 168 to 457 m in the vertical direction.

Folding
The principal fold in the Silver Belt is the Big Creek Anticline. Major mineralized deposits are localized on the north limb of the anticline, locally south of the Osburn Fault. Beds on the north limb are generally steeply dipping to overturned in the mine. Smaller sympathetic folds are notably present. On the hanging wall side of the West Chance Vein, for instance, two folds with amplitudes of about 30.5 m are noted. Bedding attitudes in some places suggest the major folds plunge to the west.

Sunshine Mine Veins
The main productive vein systems in the Sunshine Mine include the Sunshine, Chester, Polaris, Copper, Yankee Girl, and West Chance. Mineralized silver veins are present within a zone approximately 3,810 m long by 1,524 m wide and extending a vertical distance of approximately 1,890 m between 1,036 m above sea level to 853 m below sea level. The mineralization is open at depth below the 5600 Level.

Major veins strike east-west and typically dip 60° to 70° to the south. Vein strike lengths are up to 610 m, with the down-dip length two to three times the strike length and average between 0.3 and 1.5 m thick. Mineralized material occurs principally as tetrahedrite and galena with siderite and quartz as the main gangue minerals.

Mineralization
Over 40 veins have been named and mined at the Sunshine Mine. The Sunshine and Chester Veins have each produced over 90 million ounces of silver. The majority of veins strike east-west and dip about 65° to the south. Locally, dips range from 45° to 90°. Strike lengths locally exceed 610 m and dip lengths are two to three times greater than the strike length. Major veins are located between the faults at an angle of 25° to the bounding faults. Veins vary in width from a few inches to over 9 m but are typically between 0.3 and 1.5 m thick. Mineralized material includes tetrahedrite and galena with siderite and quartz as the principal gangue minerals. Accessory minerals include bournonite, pyrargyrite and magnetite.

The silver content of the tetrahedrite varies and the silver-to-copper ratio in the mineralized material ranges from 40:1 (ounce per ton silver:percent copper) up to 100:1. Tetrahedrite occurs as blebs, fracture fillings or in veinlets. Grades on the veins vary from low-grade material to well over 34,286 gpt of silver before mining dilution. Samples of over 68,571 gpt of silver have been collected in the mine. Figure 7-2 presents a longitudinal -section view looking north, showing the related mined portions of major veins of the Sunshine Mine. Veins containing higher-grade material typically, but are not limited to, favorable stratigraphic host rocks of the Ravalli group. Overall, the host rock assemblage is complexly folded and faulted. Lithology color and bed thicknesses are some of the key principal features used in stratigraphic interpretation. Alteration leaching haloes around the veins change the pro-lithology color, complicating the task of stratigraphic correlation. The relatively recent district knowledge of stratigraphic control assisted Sunshine Mine geologists in the discovery of the West Chance Vein. This method has continued to produce targets for future Resource development programs.

Vein Mineralogy
Mineralogy is quite simple in the mineralized materials of the district and at the Sunshine Mine. Typically, the Sunshine Mine mineralized material consists principally of tetrahedrite, the high silver-content copper antimony sulfide (3Cu2S • Sb2S3). The silver content of the tetrahedrite varies considerably, and the silver-to-copper ratio in the mineralized material ranges from 40:1 (ounce silver per ton:percent copper) to over 100:1. Tetrahedrite occurs as very fine grains in fracture fillings, veinlets, or discontinuous blebs in the vein-filled faults. This silver-bearing tetrahedrite is more properly called freibergite. Freibergite contains 3% to 30% silver substituting for the copper in the crystal structure. Gangue minerals are predominantly siderite (FeCO3) with lesser amounts of quartz (SiO2). Other sulfide minerals, principally galena (PbS) and minor associated sphalerite (ZnS), are present in the mine and district veins. Four veins at the Sunshine Mine contain notable galena content including the West Chance, Silver Syndicate, Chester Hook, and the recently discovered 10 Vein. Other metallic minerals observed in the local vein assemblage gangue include pyrite (FeS2), arsenopyrite (FeAsS), boulangerite (5PbS • 2Sb2S3), bournonite (2PbS • Cu2S • Sb2S3), pyrargyrite (3Ag2S • Sb2S3), and magnetite (Fe3O4).

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

CommodityProductUnitsAvg. AnnualLOM
Silver Concentrate kt 138
Silver Metal in concentrate koz 9,115255,224
Copper Metal in concentrate lbs 1,405,60839,357,029
Lead Concentrate kt 218
Lead Metal in concentrate M lbs 2.262
Antimony Metal in concentrate lbs 66,380,493

Operational metrics

Metrics
Daily mining capacity 0000
Daily processing capacity 0000
Annual processing capacity 000000
Waste tonnes, LOM 0000000
Ore tonnes mined, LOM 00000
Tonnes processed, LOM 00000000
* According to 2020 study.

Production Costs

CommodityUnitsAverage
Cash costs Silver USD 000
Total cash costs Silver USD 000000
Assumed price Lead USD 000
Assumed price Copper USD 000
Assumed price Silver USD 000
* According to 2020 study / presentation.
Net of By-Product.

Operating Costs

Currency2020
UG mining costs ($/t milled) USD 121.6 *  
Processing costs ($/t milled) USD  ....  Subscribe
G&A ($/t milled) USD  ....  Subscribe
Total operating costs ($/t milled) USD  ....  Subscribe
* According to 2020 study.

Project Costs

MetricsUnitsLOM Total
Initial CapEx $M USD  ......  Subscribe
Working capital $M USD  ......  Subscribe
Sustaining CapEx $M USD  ......  Subscribe
Closure costs $M USD  ......  Subscribe
UG OpEx $M USD  ......  Subscribe
Processing OpEx $M USD 270.1
Refining costs $M USD  ......  Subscribe
G&A costs $M USD 219.8
Total OpEx $M USD  ......  Subscribe
Income Taxes $M USD  ......  Subscribe
Royalty payments $M USD  ......  Subscribe
Gross revenue (LOM) $M USD  ......  Subscribe
Net Operating Income (LOM) $M USD  ......  Subscribe
After-tax Cash Flow (LOM) $M USD  ......  Subscribe
After-tax NPV @ 5% $M USD  ......  Subscribe
After-tax NPV @ 7.5% $M USD  ......  Subscribe
After-tax NPV @ 2.5% $M USD  ......  Subscribe
After-tax IRR, %  ......  Subscribe
After-tax payback period, years  ......  Subscribe

Heavy Mobile Equipment

Fleet data has not been reported.

Personnel

Mine Management

Source Source
Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Dec 11, 2023
....................... Subscription required ....................... Subscription required Subscription required Dec 11, 2023
....................... Subscription required ....................... Subscription required Subscription required Jan 17, 2020
....................... Subscription required ....................... Subscription required Subscription required Jan 17, 2020
....................... Subscription required ....................... Subscription required Subscription required Dec 11, 2023

Total WorkforceYear
Subscription required 2020

Aerial view:

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