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 and generating US$865 million in after-tax cash flow 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

Plan to start commissioning new mine by year-end 2019.

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 commissioning targeted for late 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 mid-2019, commissioning late 2019

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

phase 1 commissioning targeted for late 2019

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 on average more than US$83 million of after-tax operating cash flow per year in the current gold price environment over a 16-year mine life. 

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

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. As such, Phase 1 construction is targeted for 2019 with the objective of stacking ore on the heap leach pad and commissioning the ADR plant in late 2019.

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

Exceptional Exploration Upside

Strong organic growth potential with new high-grade discoveries

Equinox Gold is exploring a number of promising areas on the Castle Mountain property, with the objective of extending mineralization beyond the currently defined resource pit, and also following up on new high-grade discoveries.

Exploration strategy

Recent drilling has intersected broad intervals of low-grade mineralization cored by higher-grade structurally controlled mineralization

More than 58,100 metres of drilling was completed in 2017, aimed at upgrading material previously classified as waste or inferred resources within and adjacent to the resource pit shell. Drilling returned broad intervals of consistently low-grade mineralization, some long good-grade intercepts including 1.01 g/t gold over 180 m and 0.89 g/t gold over 148 m, and also some higher-grade intercepts including 5.49 g/t gold over 20 m and 1.62 g/t gold over 76 m. The delineation of higher-grade zones could impact the resource grade and reduce the strip ratio, and continued intercepts at depth have the potential to push the current pit bottom lower, expanding the defined resource boundary at depth.

Significant new discovery at East Ridge

On February 15, 2018, Equinox Gold announced the discovery of significant mineralization at the East Ridge target, peripheral to the current Castle Mountain resource pit. A channel sampling program covering a portion of the East Ridge target identified extensive, previously unrecognized gold mineralization on surface that was corroborated by three of the best drill holes from the Q4-2017 exploration program, with grades significantly higher than the current resource grade.

Equinox Gold will further explore the East Ridge target later in 2018, as part of an extensive 30,000 m drill program.

Hole CMM-192 intersected 2.26 g/t gold over 126.5 metres

Two rigs are currently drilling at Castle Mountain with the objective of infilling inferred resources to upgrade that material to a higher category. In addition, drilling in 2018 will follow up on higher-grade mineralization found in the andesite footwall, below the JSLA pit. Hole CMM-195 intersected 2.26 g/t gold over 126.5 m in the andesite, indicating that the footwall could be prospective for epithermal mineralization.

Surface mapping and sampling has also identified a number of promising near-mine targets on the property, some with no prior drilling. Equinox Gold is planning its exploration strategy for the larger property, with the objective of delineating additional mineralization that can extend the mine life and potentially increase the overall resource grade for the mine. The Castle Mountain team is integrating the results of the 2017 exploration program with detailed geological mapping and updating the existing 3D geological model of the deposit to gain an improved understanding of the controls on mineralization. Additional, a regional geological mapping and prospecting program is underway and the Company intends to drill more than 30,000 m later in 2018.

Project Geology

The Castle Mountain Project hosts a disseminated low-sulphidation epithermal system, similar to other epithermal systems located in the Great Basin in Nevada. Gold is primarily hosted by late-stage rhyolite volcanic units within zones of silicification and brecciation associated with northeast-southwest trending/southeast dipping fault structures that are interpreted to have developed within a collapsed caldera environment. Gold mineralization occurs as very fine-grained native (free) gold and electrum, disseminated in quartz-stockwork veins and microfractures within strongly silicified and brecciated rhyolite flows, domes, and associated sediments.

Centres of gold mineralization have formed along the main Northeast-trending structural corridor and include, from south to north, the Leslie Ann, Jumbo South, Jumbo, Hart Tunnel and Oro Belle deposits. Higher-grade concentrations of gold appear to be related to the troughs and high-angle bounding structures, and the potential intersection of these with Northwest trending, Southwest dipping faults.

What are you searching for?