Long-life gold mine producing 200,000 oz per year.

The Castle Mountain heap leach gold mine in California produced more than one million ounces of gold from 1992 to 2004. Equinox Gold intends to put the mine back into production with the expectation of producing 2.8 million oz of gold over a 16-year mine life.

Download the Castle Mountain PFS


Status Prefeasibility COMPLETE jULY 2018

Location California, USA

Production Potential 200,000 oz/year

two-phase ramp up starting in late 2019

P&P Reserves3.6 Moz @ 0.56 g/t gold 

M&I Resources4.3 Moz @ 0.56 g/t gold (inclusive)

Low-cost Mineaisc in lowest quartile of industry

Explorationnew higher-grade discoveries


Downloadcastle mountain pfs results

Past-Producing Gold Mine With Re-Start Strategy

Phase 1 production targeted for 2020.

On July 16, 2018, Equinox Gold released the results of a prefeasibility study for Castle Mountain with the objective of resuming production in a phased ramp-up scenario, starting with run-of-mine heap leaching of stockpile material from previous operations, and ramping up to a full restart that will include milling of higher-grade ore.

Key facts

Mine type Open pit
Access Paved roads, 120 km south of Las Vegas

Federal mining permit and County conditional use permit
Minor State and County permits required to restart
Ancillary permits and a new EIS required for full ramp-up

Strategy Phase 1: Initial ROM heap leach of stockpile material
Phase 2: Full restart including ROM heap leach and milling of higher grade ore
Production target Phase 1: 45,000 oz/year
Phase 2: 203,000 oz/year
Reserves P&P: 3.6 Moz @ 0.56 g/t gold
Resources M&I: 4.3 Moz @ 0.56 g/t gold (inclusive)
Inf: 2.2 Moz @ 0.40 g/t gold
Status Prefeasibility completed July 16, 2018
Phase 1 construction targeted for Q4-2019

Higher gold prices justify putting the mine back into production

The Castle Mountain Gold Mine produced more than one million ounces of gold as an open-pit heap-leach mine from 1992 to 2004, when the mine was shut down due to low gold prices. Material below 0.50 g/t gold mined from the Oro Belle and Jumbo pits was placed into the JSLA pit.

Higher gold prices justify putting the mine back into production to process that stockpile material, which is economic using current gold prices. Recent drilling, aimed at upgrading material previously classified as waste or inferred resources within and adjacent to the pit shells, has discovered consistently good grades and also some higher-grade intercepts. Drilling has also discovered higher-grade mineralization below the backfill material, including a new zone of mineralization in the andesite footwall, which was previously thought to be unmineralized.

Production Strategy

Phased Ramp-up

To access existing and potentially new resources, Equinox Gold intends to recommence production in a phased ramp-up scenario, as outlined below. Based on the July 2018 prefeasibility study, at $1,250/oz gold the project has a net present value (discounted at 5%) of US$406 million.

Phase 1

  • Re-establish onsite operations using the current permit 
  • Initial mining and run-of-mine (“ROM”) heap leach processing of the historical JSLA pit stockpile material
  • Production target: 45,000 oz/year for three years
  • Permit requirements: Federal permit in place, ancillary State water and air permits
  • Construction requirements: Construct small leach pad and gold recovery plant
  • Timeline target: Construction Q4-2019, production H2-2020

Phase 2

  • Higher throughput with milling of higher-grade ore and ROM heap of lower-grade material 
  • Production target: 203,000 oz/year
  • Permit requirements: New Environmental Impact Assessment and expansion permit
  • Water requirements: Source additional water for increased throughput


On July 16, 2018, Equinox Gold released the results of a prefeasibility study for the Castle Mountain Gold Mine in California, USA. The project will be developed as an open-pit heap leach mine starting with Phase 1 run-of-mine (“ROM”) heap leaching of stockpile material from previous operations and ramping up to a full restart in Phase 2 that will include milling of a limited stream of higher-grade material and ROM leaching of the balance. With 3.6 million oz of gold reserves, Castle Mountain will be a robust, low-cost gold mine producing 2.8 million ounces of gold over a 16-year mine life. 

Download the Prefeasibility Study Technical Report, or download the slide deck discussing the results.

2018 Prefeasibility Study Highlights (US$)

Gold price (base case) $1,250/oz
P&P Reserve 3.6 Moz Au @ 0.56 g/t Au
M&I Resource (inclusive of reserves) 4.3 Moz Au @ 0.56 g/t Au
Mine Life 16 years
Phase 1 production (yrs 1-3)
Phase 2 production (yrs 4-16)
Avg. 45 koz gold
Avg. 203 koz gold
Strip Ratio / Recovery 3.6 / 79%
Total Production (LOM) 2.8 Moz gold
Initial Capex
Phase 1
    Phase 2
$347 M 
    Phase 1 $52 M 
    Phase 2 $295 M 
Sustaining Capex $142 M 
Cash Cost (LOM) $712/oz
AISC (LOM) $763/oz
Cash Flow (after tax) (LOM) $865 M (net of initial capital)
Phase 1 commissioning Late 2019
NPV 5% (after tax) $406 M ($534 M at $1,350/oz gold)
IRR (after tax) 20% (25% at $1,350/oz gold)

Next Steps

The Castle Mountain Gold Mine produced more than 1.3 million ounces of gold from 1992 to 2004, when production ceased due to low gold prices. The property was substantially reclaimed from 2004 to 2012, but 3.6 million ounces of gold reserves remain and are economic at current gold prices. The Company has maintained its permits in good standing since operations ceased and has the key permits (San Bernardino County Conditional Use Permit and a Federal Record of Decision) and the water supply required to commence Phase 1 production. Phase 1 construction is targeted for Q4-2019 with the objective of restarting operations in 2020.

During Phase 1 construction and operations, the Company will undertake the permitting and water studies required to commence Phase 2 production. 

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