Palmer VMS

Defining high-grade, low-capex type targets within a multi-deposit, district-scale environment

This is an advanced stage Cu-Zn-Au-Ag exploration project in Southeast Alaska with road access and located only 60 km (37 miles) from the deep sea port at Haines, Alaska.

The project hosts two NI 43-101 compliant resources, the Palmer Deposit and AG Zone Deposit, with a total consolidated mineral resource of 4.68 million tonnes of 10.2% zinc equivalent in the indicated category and 9.59 million tonnes of 8.9% zinc equivalent in the inferred category.  A Preliminary Economic Assessment ("PEA") was completed in June 2019 (filed July 18, 2019, amended March 7, 2022; filed on, which presents a low capex, low operating cost, high margin underground mining operation with attractive environmental attributes. Highlights of the PEA are provided below.

This project is operated by Constantine under a Joint Venture partnership between Constantine (45%) and Dowa Metals & Mining Co., Ltd. (55%).


Location Coastal Southeast Alaska, USA
Ownership 45% Constantine, 55% Dowa Metals & Mining on select claims

Preliminary Economic Assessment completed June 2019  (News Release June 3, 2019); Amended March 7, 2022 (News Release March 11, 2022)

Deposit Type Volcanogenic Massive Sulphide (VMS Deposit)
Property Size 25,084 hectares (61,984 acres)
Host Rock Carbonate-rich Pillow Basalt
Age Upper Triassic (Norian); same age as Greens Creek and Windy Craggy deposits
Main Economic Elements Copper & Zinc, with Gold and Silver credits
Approximate Geometry Steeply stacked sulphide lenses

SW Zone I: approx. maximum true thickness of 30m, dip length 220 m, strike length 350 m

SW Zone II/III: approx. maximum true thickness of 24m, dip length 350 m, strike length 425 m

SW EM Zone: approx. maximum true thickness of 74m, dip length 250 m, strike length 370 m

AG Zone: approx. maximum true thickness of 47m, dip length 200 m, strike length 550 m
Resource Estimate

Palmer Deposit (cut-off $75/t NSR) (news release Sept 27, 2018)
4.68 MT Indicated @ 5.23% Zn, 1.49% Cu, 30.8 g/t Ag, 0.30 g/t Au, 23.9% BaSO4  
5.34 MT Inferred   @ 5.20% Zn, 0.96% Cu, 29.2 g/t Ag, 0.28 g/t Au, 22.0% BaSO4

AG Zone Deposit (cut-off 5% ZnEq) (news release Dec 18, 2018)
4.26 MT Inferred  @ 4.64% Zn, 0.12% Cu, 0.96% Pb, 119.5 g/t Ag, 0.53 g/t Au, 34.8% BaSO4

Proposed Mine Design Underground with ramp access from base of mountain

Location Map

RW and SW Geology_2019


  • Large, district-scale property position totaling approximately 25,084 hectares (61,984 acres) (inclusive of the ‘Haines Block’ leased from the Alaska Mental Health Trust Authority and the pre-existing Palmer state and federal claims).
  • Excellent access - located adjacent to a paved Alaska state highway, with a short distance (60 kilometers/37 miles) to year-round deep-sea port facilities in Haines, Alaska, and Pacific Ocean access to Asian mineral concentrate markets.
  • Dowa Metals and Mining Alaska Ltd. earned into a 49% interest in Palmer with expenditures of US$22 million over the four-year period from 2013-2016 with Constantine retaining a 51% interest and acting as operator. In 2021, Dowa increased it’s interest in the Palmer project to approximately 55% with Constantine remaining as the project operator.
  • Dowa Alaska’s parent company, Dowa Metals and Mining Co., Ltd., is headquartered in Tokyo, Japan. The partnership with Dowa significantly de-risks the Palmer project as Dowa brings over 100 years of experience in the exploration, production and smelting of VMS deposits.

Preliminary Economic Assessment (PEA) Highlights

Highlights of the PEA, assuming 2019 base case metal price of $1.22 per pound zinc, $2.82 per pound copper, $16.3 per ounce silver, $1296 per ounce gold and $220 per metric tonne barite, include:

  • $354M pre-tax Net Present Value (“NPV”) at 7% discount rate
  • $266M after-tax NPV at 7% discount rate
  • 24% pre-tax Internal Rate of Return (“IRR”) and 21% post-tax IRR
  • Mine life of 11 years after 24-months pre-production (based on current mineral resource)
  • 3,500 tonnes-per-day steady state mining and processing rate
  • Operating cost of $54.2/tonne (mining, processing, General &Administrative)
  • Operating plus sustaining capital cost of $65.4/tonne
  • Net operating income of $92.6/tonne ($81.4/tonne including sustaining capital costs)
  • Zinc cash cost including sustaining capital of $0.11 per lb net of by-product credits
  • Pre-production development capital cost of $278 million
  • Sustaining capital and closure cost of $140 million; total Life of Mine (“LOM”) capital cost of $418 million
  • Post-tax payback period of 3.3 years
  • 12.48 million tonnes (“Mt”) mined at a diluted head grade of 4.24% zinc, 0.81% copper, 49.6 grams per tonne (“g/t”) silver, 0.33 g/t gold and 22.6% barite (“BaSO4”)
  • LOM recovered metal production of 1,068 M lbs of zinc, 196 M lbs of copper, 18 M oz of silver, 91 K oz of gold and 2.89 M tonnes of BaSO4
  • Important US source of the critical mineral barite

For summary of the PEA, see Constantine press release dated June 3, 2019 and March 11, 2022. The report is filed at, July 18, 2019, amended March 7, 2022.
NOTE: The PEA is preliminary in nature and includes inferred mineral resources that are too speculative geologically to have economic considerations applied to them that would enable them to be categorized as mineral reserves. There is no certainty that PEA results will be realized. Mineral resources that are not mineral reserves do not have demonstrated economic viability.

Link to the Palmer Project Technical Report: Preliminary Economic Assessment, Effective Date June 3, 2019.


  • The original discovery of surface mineralization was made in 1969 by local prospector Merrill Palmer, followed by a number of exploration campaigns by various companies throughout the subsequent years. Drilling done by Constantine made the significant deposit discoveries leading to the first resource estimate for South Wall and RW Zones (The Palmer Deposit) in 2010 and the discovery of the AG Zone Deposit in 2017 validating the potential of this emerging base metal district.
  • A resource estimate done in late 2018 brought the total resource for both the Palmer Deposit and the AG Zone Deposit to a total of 10 million tonnes (*see Resource Table below) allowing Constantine to reach the major milestone of delivering a positive Preliminary Economic Assessment (PEA) in mid-2019.


  • Palmer is hosted by the same Late Triassic volcanogenic massive sulphide (VMS) belt as the high-grade producing Greens Creek silver-zinc-gold-lead mine, and the giant 298 Mt Windy Craggy copper deposit - a world class environment.
  • Palmer displays volcanic-hosted base metal mineralization associated with interpreted felsic exhalative horizons in a thick sequence of basalt flows with interbeds of sediments, andesite flows and tuffs and fragmental and massive rhyolites.
  • Notable prospect areas, all in close proximity, include the South Wall and RW zones, AG zone, Mount Henry Clay, Cap, Hanging Glacier, the Gullies, Boundary and Red Creek.

Readers are cautioned that mineral deposits on adjacent or similar properties are not indicative of mineral deposits on the Company’s property and there is no certainty of the same or similar deposits on the  Company’s property.

Palmer Access and Infrastructure

Looking up Glacier Creek

Palmer Regional Prospects

Palmer SW Long Section

Mineral Resources


  • Steep geometry of thick, continuous zones of massive sulphide coupled with the potential to access by short lateral drifts at lower elevations makes for potential lower cost mining
  • Very good response to conventional metallurgical testing, with high metal recoveries produced at moderate grind sizes. Initial locked cycle flotation tests yielded good quality, smeltable copper and zinc concentrates.
  • Constantine has completed preliminary environment baseline studies maintains annual monitoring programs.

Palmer Deposit 3D


  • The Palmer project includes numerous drill-ready high-grade prospects that define more than 15 kilometers of favorable mineral trends, all hallmarks of a significant massive sulphide system and opportunity for the discovery of multiple deposits.

Palmer Regional Geology


  • Palmer is located in the same metallogenic belt as Greens Creek and Windy Craggy VMS deposits - both widely recognized to be world class systems.
  • Palmer compares, in both grade and size, to the most highly prospective VMS belts currently undergoing significant exploration efforts. As a deposit class, VMS deposits are attractive for being polymetallic (multi-metal) and having high dollar value per tonne.
  • Closest to Palmer is the Windy Craggy deposit, with a 297 million tonne resource, it is the fourth largest VMS deposit in the world by size, and tops the list as the largest of the copper rich (Beshi style) category of VMS deposits.
  • Hecla Mining’s Greens Creek deposit is an estimated ~25 million tonnes grading 5.1% lead, 13.9% zinc, 5.61 grams per tonne gold and 706 grams per tonne silver, one of the world’s richest VMS deposits.
  • In addition to solid cash flow from base metals, Greens Creek is among the top five global silver producers in addition to its gold production of more than one million ounces since mining commenced in 1989.
  • In 2008, Hecla Mining paid $750 million to purchase the 70% interest of the 7.7 million tonne mining reserve to increase its ownership to 100%. This places the value of the Greens Creek deposit at over $1 billion - a remarkable value for a mine in operation for only 20 years.

Readers are cautioned that mineral deposits on adjacent or similar properties are not indicative of mineral deposits on the Company’s property and there is no certainty of the same or similar deposits on the Company’s property.

Technical Report

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