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United States
Rochester Mine

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 Location:
29 km NE from Lovelock, Nevada, United States

  Address:
I-80
Lovelock
Nevada, United States
89419
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  • Filings & News

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Overview

StageProduction
Mine TypeOpen Pit
Commodities
  • Silver
  • Gold
Mining Method
  • Truck & Shovel / Loader
Processing
  • Heap leach
  • ROM/dump leach
  • Merrill–Crowe
  • Cyanide (reagent)
Mine Life15 years (as of Jan 1, 2020)
July 29, 2020 - Prepared to begin construction on upcoming expansion at Rochester - The Company received authorizations necessary to advance the expansion under Plan of Operations Amendment 11 (“POA 11”) at Rochester. Coeur expects to commence construction on the project in early August 2020.
Latest NewsCoeur Announces Details of Rochester Expansion in Updated Technical Report     December 16, 2020


Owners & OPERATOR

Source: p. 14
CompanyInterestOwnership
Coeur Mining, Inc. 100 % Indirect
Coeur Rochester, Inc. (operator) 100 % Direct
Coeur owns 100% of Coeur Rochester, Inc. ("Coeur Rochester"), which has operated the Rochester mine, a silver and gold surface mining operation located in northwestern Nevada, since 1986.

Deposit Type

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


Summary:

Silver and gold mineralization at the Rochester and Nevada Packard mines is hosted by the Rochester and Weaver Formation volcanic and epiclastic rocks of the Koipato Group The Rochester Formation exposed in the Rochester pit is comprised of rhyolite flows and tuffs, breccias, thin intervals of spherulitic and lithophysae tuffs, and fine-grained volcaniclastic rocks. The volcanic stratigraphy shows little continuity laterally and vertically, and is typically mapped as undifferentiated Rochester tuffs and flow banded rhyolites. The Rochester Formation is extremely fractured with a thickness estimated to be 1,800 feet in the Rochester Mine area.

Quartz veins and veinlets typically exhibit parallel and cross-cutting features, indicating multiple mineralizing events. Milky white quartz is typically overprinted by the ore carrying gray-to-tan cryptocrystalline quartz veins and stockwork. Tourmaline is rare in the milky white quartz at Rochester but can be seen in abundance outside of the property. High grade mineralization at Rochester is contained within discontinuous and anastomosing veins that range in thickness from 4 inches to 3 feet. These veins are steeply dipping at the surface (>60 degrees) but at depth become shallower (<30 degrees) and lower grade. Lower grade mineralization occurs as dissemination in veins, breccia stockwork, and throughout the rocks. Vein trends in plan strike northerly. In cross-section, mineralization associated with faults dips 35 to 65 degrees west while mineralization occurring near the formational contact exhibits shallow dips (0 to 30 degrees) both to the east and west.

All ore is hosted in the oxide zone where the Rochester-Weaver contact is the primary host for gold-silver mineralization, followed and influenced by mineralized fault zones with disseminations away from the faults. The contact is extensively brecciated post conglomerate lithification and healed by silica. Low grade mineralization is controlled by both hypogene processes and supergene enrichment. These low grade systems vary in width (both along strike and down dip) from tens to hundreds of feet. Below the oxidation zone ore grade typically drops off but can be found in narrowly focused quartz veins. The Rochester and Nevada Packard deposits are completely oxidized to a depth of 300-500 feet and partially oxidized to a depth of over 700 feet.

Currently identified mineralization at the Rochester deposit is discontinuous over an area of 5,100 feet north to south and 6,000 feet east to west. Mineralization dips to the west at an average of 300, nearly parallel with topography producing an average true depth of 700 feet. The discontinuous nature of mineralization increases near the edges of known mineralization.

Supergene processes are thought to be responsible for the remobilization and enrichment of silver at Rochester and possibly Nevada Packard. Supergene oxide minerals present include acanthite, chlorargyrite, embolite, hematite, kaolinite, halloysite, goethite, amorphous iron oxides, chalcanthite, chalcophanite, melanierite, jarosite, manganese oxides, and native silver. Acanthite and chlorargyrite are the most abundant oxide silver phases. Below the oxidation zone the hypogene profile is preserved. Sulfide zone minerals in the hypogene profile include pyrite, sphalerite, galena, tetrahedrite, chalcopyrite, arsenopyrite, pyrargyrite, and possibly pyrrhotite and owyheeite (Vikre, 1981).

Mineralization at Nevada Packard is similar to that exploited in the Rochester pit in that northeast trending faults dipping to the west are the most dominant mineralized trends and silver and gold are associated with vein arrays. One difference in the Packard mineralization, however, is that silver tends to be of higher grade than at Rochester while the gold grades tend to be lower. The mineralized zones are broad and disseminated but smaller than those at Rochester, typically no larger than 200 feet wide. The discontinuous broad mineralized zones cover an area of 2,500 feet by 2,300 feet and up to 600 feet in depth. Mineralization below 300 feet rapidly decreases in number of occurrences and in width.


Mining Methods

  • Truck & Shovel / Loader


Summary:

Since 1986, Coeur has mined at Rochester by conventional open pit, drill and blast, truck, and loader methods. The mining operation at Rochester is currently at planned capacity under the current PoO 10, and is expected to continue through the end of 2023. The planned mining areas have been cleared and grubbed and all pre-stripping has been completed. In 2017, Coeur plans to continue the process of obtaining permits for additional pad capacity, additional RDS facilities, and extensions of the Rochester Pit, which are expected to be received by mid-2021. This expanded capacity is anticipated to further extend Rochester’s active mine life, based on existing Mineral Reserve estimates through the end of 2029. Internal waste movement does occur as it is encountered and is placed in the mine’s RDS facilities.

Operations at Rochester consist of mining from in situ and stockpiled open pit sources that are either: (1) Fed directly into the primary crusher dump pocket; (2) Crushed at an in-pit crusher system; or (3) Placed directly onto a heap leach pad for ROM processing.


Crushing and Grinding


Processing

  • Heap leach
  • ROM/dump leach
  • Merrill–Crowe
  • Cyanide (reagent)

Source: Subscription required

Summary:

Ore extracted from the open pit mining operation is hauled to one of two crushing circuits. These circuits utilize three stages of crushing and are referred to as the X-pit and N-pit crushing systems.

ROM ore is utilized as a secondary ore source to be treated on the leach pads. ROM is classified as blasted but uncrushed ore and is directly transferred directly to the leach pads from the mining operations. ROM ore is transferred via 777 haul trucks to the active leach pad and is treated with lime from the N-pit lime silo for appropriate pH control during the leaching process.

Currently there are four dedicated valley-fill heap leach facilities at the Rochester Mine, referred to as Stage I, II, III and IV. The Rochester Mine leach pads are typically constructed in 30 foot lifts to heights of 300 feet above liner.

On the heap leach pads cyanide solution is applied via drip tube at a rate of ~0.004 gallons per minute per square foot,, and allowed to perco ........

Recoveries & Grades:

CommodityParameter20192018201720162015201420132012
Silver Head Grade, oz/ton 0.460.520.530.570.630.570.550.51
Gold Head Grade, oz/ton 0.0030.0040.0030.0030.0030.0040.0030.004
Silver Recovery Rate, %  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
Gold Recovery Rate, %  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
Subscription required - Subscription is required.

Production:

CommodityUnits202020192018201720162015
Silver koz  ......  Subscription required ^  ......  Subscription required  ......  Subscription required4,7144,5644,631
Gold oz  ......  Subscription required ^  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
Silver Equivalent koz  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
All production numbers are expressed as metal in doré. ^ Guidance / Forecast.
Subscription required - Subscription is required.

Operational Metrics:

Metrics2019201820172016201520142011
Tonnes milled  ......  Subscription required  ......  Subscription required  ......  Subscription required19,555,998 tons16,414,302 tons13,154,429 tons1,782,971 tons
Subscription required - Subscription is required.

Reserves at December 31, 2019:

CategoryTonnage CommodityGradeContained Metal
Proven 249,815,000 tons Silver 0.45 oz/ton 112,286,000 oz
Proven 249,815,000 tons Gold 0.003 oz/ton 710,000 oz
Probable 13,577,000 tons Silver 0.38 oz/ton 5,187,000 oz
Probable 13,577,000 tons Gold 0.002 oz/ton 27,000 oz
Proven & Probable 263,392,000 tons Silver 0.45 oz/ton 117,473,000 oz
Proven & Probable 263,392,000 tons Gold 0.003 oz/ton 737,000 oz
Measured 194,330,000 tons Silver 0.35 oz/ton 67,602,000 oz
Measured 194,330,000 tons Gold 0.002 oz/ton 450,000 oz
Indicated 42,015,000 tons Silver 0.36 oz/ton 15,195,000 oz
Indicated 42,015,000 tons Gold 0.002 oz/ton 96,000 oz
Measured & Indicated 236,345,000 tons Silver 0.35 oz/ton 82,797,000 oz
Measured & Indicated 236,345,000 tons Gold 0.002 oz/ton 546,000 oz
Inferred 171,042,000 tons Silver 0.36 oz/ton 60,803,000 oz
Inferred 171,042,000 tons Gold 0.002 oz/ton 378,000 oz

Commodity Production Costs:

CommodityUnits20202019201820172016
Total cash costs (sold) Silver USD  ......  Subscription required ^  ......  Subscription required  ......  Subscription required 12 / oz
Total cash costs (sold) Gold USD  ......  Subscription required ^  ......  Subscription required  ......  Subscription required 889 / oz
Total cash costs (sold) Silver Equivalent USD  ......  Subscription required 13.2 / oz 11.9 / oz
^ Guidance / Forecast.
Subscription required - Subscription is required.

Financials:

Units20202019201820172016201520142013
Capital expenditures (planned) M USD  ......  Subscription required
Capital expenditures M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required 25.3   11.9   29.4  
Sustaining costs M USD  ......  Subscription required  ......  Subscription required
Revenue M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required 143.93   123.77   119.25  
After-tax Income M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required 10.3   6.92   -8.68  
Operating Cash Flow M USD  ......  Subscription required  ......  Subscription required 32.1  
Subscription required - Subscription is required


Heavy Mobile Equipment as of March 5, 2018:
HME TypeModelQuantity
Drill 3
Loader (FEL) ....................... Subscription required 1
Shovel (hydraulic) ....................... Subscription required 1
Shovel (hydraulic) ....................... Subscription required 1
Truck (haul) ....................... Subscription required 11
Truck (haul) ....................... Subscription required 2
Subscription required - Subscription is required.

Mine Management:

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Sep 17, 2020
....................... Subscription required ....................... Subscription required Subscription required Sep 17, 2020
....................... Subscription required ....................... Subscription required Subscription required Sep 17, 2020
....................... Subscription required ....................... Subscription required Subscription required Sep 17, 2020
Subscription required - Subscription is required.

Staff:

EmployeesYear
Subscription required 2019
Subscription required 2018
Subscription required 2017
Subscription required 2016
Subscription required 2015

Corporate Filings & Presentations:

DocumentYear
................................... Subscription required 2020
................................... Subscription required 2019
................................... Subscription required 2019
................................... Subscription required 2019
................................... Subscription required 2019
................................... Subscription required 2018
................................... Subscription required 2018
................................... Subscription required 2018
................................... Subscription required 2018
Annual Report 2017
Technical Report 2017
Year-end Mineral Reserves 2017
Annual Report 2016
Press Release 2016
Press Release 2016
Year-end Mineral Reserves 2016
Annual Report 2015
Technical Report 2015
Year-end Mineral Reserves 2015
Annual Report 2014
Annual Report 2013
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News:

NewsDate
Coeur Announces Details of Rochester Expansion in Updated Technical Report December 16, 2020

Aerial view:

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