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Canada

Spectrum-GJ Project

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Overview

Mine TypeOpen Pit
StagePreliminary Economic Assessment
Commodities
  • Copper
  • Gold
  • Silver
Mining Method
  • Truck & Shovel / Loader
Mine Life... Lock
SnapshotThe Spectrum-GJ Cu-Au project area comprises a combination of the properties: the Spectrum property and the GJ property.

Owners

SourceSource
CompanyInterestOwnership
Skeena Resources Ltd. 100 % Direct
Skeena Resources Limited holds a 100% interest in the Spectrum property and an option to acquire a 100% interest in the adjoining GJ property.

On May 1, 2020, Skeena reported the closing of the asset purchase agreement between Skeena and Newcrest Red Chris Mining Limited (“Newcrest”) dated February 3, 2020 to sell 100% of the Company’s interest in the GJ Copper-Gold Property (the “GJ Property”) to Newcrest for C$7.5 million paid in cash, and the assumption by Newcrest of future payment obligations and royalties on the GJ Property.

Deposit type

  • Porphyry
  • Vein / narrow vein

Summary:

The Project Area hosts two principal styles of mineralization that have been the target of past and current exploration. The first and older style is porphyry Cu-Au mineralization related to intrusion and alteration by Late Triassic alkalic to sub-alkalic diorite to monzonite dykes and stocks exemplified by the Central Zone and Donnelly Deposit. The second comprises later, structurallyhosted and high-grade gold zones associated with shearing, fracture zones and quartz-carbonate vein/fault controlled pyrite, arsenopyrite, sphalerite, galena and chalcopyrite hosted by altered volcanic units and monzonite dykes.

Porphyry-Style Mineralization - Central Zone
Porphyry-style Cu-Au mineralization occurs within a north-south trending, moderately west dipping and fault-bounded structural panel of Triassic Stuhini volcaniclastic lithologies intruded by syn- to late-mineral monzonite dykes. Porphyry- style mineralization has been defined over a strike length of 1,000 m, with widths of 70 m to 200 m, it has been tested to 400 m downdip and it remains open along strike and downdip.

Mineralization occurs as quartz-pyrite-chalcopyrite with or without magnetite veinlets, stockworks, fracture fills and fine grained disseminations of pyrite and chalcopyrite. Metal grades appear to be directly related to the abundance of quartz-sulphide-magnetite vein development.

Porphyry-Style Mineralization - Donnelly Deposit
Of the many porphyry Cu-Au prospects located on the GJ claims block, the most advanced is an area measuring 3.5 km east-west and north-south where disseminated, fracture, quartz vein and quartz stockwork-controlled pyrite with variable chalcopyrite, rare bornite and trace molybdenite mineralization containing elevated gold values occurs. This area contains the Donnelly Deposit, the North Donnelly deposit and the GJ and North zones.

Typically, the best chalcopyrite mineralization occurs where pyrite is weaker and IP chargeability responses are moderate, which generally occurs on the flanks of more intense chargeability anomalies. Secondary magnetite, generally associated with chalcopyrite, is found as disseminations, irregular clots, in veins with K- feldspar with or without chlorite and/or epidote and/or as fillings in single or sheeted fractures that are one to three millimetres thick and millimetres to 10 cm apart. Exceptions to this association (the Donnelly Deposit and portions of the North zone) appear to be where magnetite has been altered to hematite.

Porphyry-Related, Vein-Hosted Mineralization
The second style of mineralization found on the Project Area comprises higher grade gold mineralization that post-dates the porphyry Cu-Au mineralization described above. It is structurally controlled in that it occurs in veins, fracture zones and stockwork crackle zones and as gold- bearing quartz-carbonate-sulphide veinlets and stockworks proximal to faults and shear zones. Petrographic work by Oliver (2016) indicates gold is associated with late fractures/microveinlets in high sulphide veinlets cutting arsenopyrite, which is one of the younger veining events. Gold also occurs as free gold within strongly fractured and strongly chlorite-sericite-calcite-pyrite altered zones with no associated sulphide veining but close associations to coarse grained laths of chlorite and sericite, and only a weak linkage to secondary K-feldspar or quartz. Gold mineralization often shows additional enrichment of Ag, Cu, Pb, Zn, As and Sb.

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

CommodityUnitsLOM
Copper B lbs 1
Gold M oz 1.6
Silver M oz 7.5
All production numbers are expressed as payable metal.

Operational metrics

Metrics
Daily milling capacity 30,000 t *
Stripping / waste ratio 0.71 *
Waste tonnes, LOM 134.71 Mt *
Ore tonnes mined, LOM 217.23 Mt *
Total tonnes mined, LOM 351.14 Mt *
Tonnes milled, LOM 213.74 Mt *
* According to 2017 study.

Production Costs

CommodityUnitsAverage
Cash costs Copper USD 1.37 / lb * **  
Cash costs Gold USD 461.56 / oz * **  
All-in costs Copper USD 1.81 / lb * **  
All-in costs Gold USD 730.97 / oz * **  
Assumed price Copper USD 2.75 / lb *  
Assumed price Silver USD 17.8 / oz *  
Assumed price Gold USD 1.25 / oz *  
* According to 2017 study / presentation.
** Net of By-Product.

Operating Costs

Currency2017
Total operating costs ($/t milled) CAD 14.3 *  
* According to 2017 study.

Project Costs

MetricsUnitsLOM Total
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Required Heavy Mobile Equipment

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Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Nov 10, 2023

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