Producing gold in California

Castle Mountain achieved commercial production in November 2020. Loaded carbon from Castle Mountain is processed in the carbon stripping and smelting plant at the Company’s Mesquite Mine, 200 miles south in California, resulting in increased operating efficiencies for both mines.

Status In production

Location California, USA

Production  25,000-35,000 oz in 2022

P&P Reserves  4,168 koz @ 0.51 g/t gold 

M&I Resources 1,470 koz @ 0.62 g/t gold 1

Inferred Resources 1,422 koz @ 0.63 g/t gold 

Mining Style Open-pit heap leach

Downloadcastle mountain technical report

  1. M&I Resources are exclusive of reserves. See Operations / Reserves & Resources and Cautionary Notes


The Castle Mountain open-pit heap leach gold mine in San Bernardino County, California, approximately 200 miles north of Mesquite. Under a previous owner, Castle Mountain produced more than 1.3 million ounces of gold from 1992 to 2004, when the mine was closed due to low gold prices. With more than 4 million ounces of gold resources remaining, the previous owner knew the mine would eventually go back into production and kept the operating permits in good standing. 

Equinox Gold acquired Castle Mountain in December 2017 and completed a pre-feasibility study in 2018 with the intention of restarting operations. The pre-feasibility study outlined a two-phase development plan, with annual average gold production of approximately 40,000 oz during Phase 1 using existing operating permits, and a Phase 2 expansion to more than 200,000 oz of gold per year. 

Phase 1 construction activities commenced in October 2019 and commercial production was achieved in November 2020. The Castle Mountain team won the 2020 Chairman’s Safety Award for completing construction with no lost-time injuries.

Phase 1 consists of a run-of-mine heap leach operation processing primarily stockpiled ore from previous operations. With operations underway, Equinox Gold is preparing to permit the Phase 2 expansion, as described in Growth Projects

Mine Type Open-pit heap leach
Operating Since 2020
Current P&P Reserve 4,168 Koz @ 0.51 g/t Au
Current M&I Resource * 5,919 Koz @ 0.54 g/t Au
Annual Production  25,000 - 35,000 oz gold in 2022
Mining Rate 12,700 tpd ore to leach pad
Recoveries ~72% 
AISC  $1,550-$1,620/oz in 2022

* Resources are inclusive of Reserves.


Mining is performed using owner-operated conventional truck and shovel open-pit mining methods and run-of-mine ore is hauled directly to the leach pad for processing. Loaded carbon is shipped to the Company’s Mesquite mine approximately 200 miles south, eliminating the need for an elution circuit at Castle Mountain and optimizing plant capacity at Mesquite.

For 2022, Equinox Gold expects Castle Mountain to produce between 25,000-35,000 oz of gold at AISC of $1,550-$1,620 per ounce of gold sold. Production is expected to increase with lower costs in future years as the mine benefits from optimization efforts to both the leach pad and plant. 



On July 16, 2018, Equinox Gold released the results of a prefeasibility study for the Castle Mountain Gold Mine in California, USA. The prefeasibility contemplates developing the project in a phased ramp-up scenario. Phase 1 would be developed as an open-pit run-of-mine (“ROM”) heap leach mine leaching stockpile material from previous operations. Phase 2 would 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 would 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

Phase 1 $58 M 
Phase 2 $175 M + Fleet
Sustaining Capex $142 M 
Cash Cost (LOM) $712/oz
AISC (LOM) $763/oz
Cash Flow (after tax) (LOM) $865 M (net of initial capital)
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 the project maintained its permits in good standing since operations ceased and had the key permits (San Bernardino County Conditional Use Permit and a Federal Record of Decision) required to commence Phase 1 production. The mine recommenced operations in September 2020 and is advancing a potential expansion that will increase production to approximately 200,000 ounces per year.

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