i-80 Gold Announces Positive Feasibility Study and Initial Mineral Reserves for Granite Creek Underground; After-Tax NPV(5%) of $118 Million at $2,750/oz Au Increasing to $598 Million at $4,500/oz Au
Original announcement by orestocks on
- Company
- i-80 Gold Corp.
- Ticker
- IAU.TO
- Exchange
- Unavailable
- Region
- Nevada, USA
- Primary commodity
- Gold
- Secondary commodities
- None reported
- Document categories
- Resource update, Economic study, Metallurgy
- Extracted
- 2026-09-22 00:04:45 UTC
Analysis by Minestarters Atlas
Minestarters Atlas analysis
Summary
i-80 Gold announced a positive Feasibility Study for its Granite Creek Underground gold project in Nevada, outlining an after-tax NPV(5%) of $118 million at a base case gold price of $2,750/oz. The study establishes initial Proven and Probable Mineral Reserves of 556,500 oz Au at 7.87 g/t Au and significantly increases Measured and Indicated resources by 229% to 859,500 oz Au. The project, which is already ramping up production, benefits from an optimized processing strategy utilizing the company's Lone Tree autoclave and CIL plant, leading to lower operating costs and an estimated LOM AISC of $2,273/oz Au (excluding refurbishment capital).
Reasoning: i-80 Gold announced a positive Feasibility Study for its Granite Creek Underground project, outlining robust economics with an after-tax NPV(5%) of $118 million at a base case gold price of $2,750/oz. The study establishes initial Proven and Probable Mineral Reserves of 556,500 oz Au and significantly increases Measured and Indicated resources by 229%. The optimized processing strategy, utilizing the company's Lone Tree Plant, is expected to reduce costs and increase production. The project is fully permitted and already in production ramp-up.
Positive factors
- Positive Feasibility Study results with robust economics
- Significant increase in Measured and Indicated resources
- Initial Proven and Probable Mineral Reserves established
- Optimized processing strategy with lower costs at Lone Tree Plant
- Fully permitted and operating mine ramping up production
Negative factors
- S-K 1300 classification as PFS despite NI 43-101 FS
- Reliance on third-party processing until Lone Tree Plant commissioning
- Historical drill results for CX Zone lack QA/QC data
Facts used in scoring: 8
Classification and evidence
DFS Bankablepositive
AACE Class 2-1 study complete and within the staleness window.
Why it applies: The document states that the NI 43-101 technical report constitutes a feasibility study, indicating a high level of engineering and cost estimation maturity.
Evidence · text
“a technical report prepared under National Instrument 43-101 – Standards of Disclosure for Mineral Projects ("NI 43-101") which, in the opinion of the qualified persons, constitutes a feasibility study under NI 43-101 (the "NI 43-101 FS" or the "FS")”
PEA Onlyneutral
Only Class 4 / Initial Assessment economics available. Not bankable.
Why it applies: The S-K 1300 technical report is classified as a Pre-Feasibility Study, which is equivalent to a PEA under this regime.
Evidence · text
“a technical report summary prepared under Subpart 1300 of Regulation S-K ("S-K 1300") which, in the opinion of the qualified persons, constitutes a pre-feasibility study under S-K 1300 (the "S-K 1300 PFS")”
High IRRpositive
Post-tax real unlevered IRR in the strong tier or better.
Why it applies: The after-tax NPV(5%) of $118 million at $2,750/oz Au and $598 million at $4,500/oz Au indicates a robust project with strong returns, although IRR is not explicitly stated.
Evidence · text
“After-Tax NPV(5%) of $118 Million at $2,750/oz Au Increasing to $598 Million at $4,500/oz Au”
Long Reserve Lifepositive
Reserve life index in the top tier of the single ladder.
Why it applies: The mine life is approximately 8.5 years, which is within the adequate range for reserve life.
Evidence · table
“8.5”
Context: Mine Life
Bottom Quartile Costpositive
P0-25 of the relevant commodity cost curve.
Why it applies: The LOM AISC of $2,273/oz Au (excluding Lone Tree Refurbishment Capital) is competitive for gold production.
Evidence · table
“$2,273”
Context: All-in Sustaining Costs - LOM(4,5) (Excl. Lone Tree Refurbishment Capital)
Conservative Pricingpositive
Conservative on the worst of the spot, 3-year and consensus comparisons.
Why it applies: The base case gold price of $2,750/oz is below the illustrative spot price sensitivity of $4,500/oz, suggesting a conservative approach.
Evidence · table
“$2,750”
Context: Gold Price
Fully Permittedpositive
Key permits granted with no unresolved challenge.
Why it applies: The Granite Creek Underground mine is stated to be fully permitted.
Evidence · text
“The Granite Creek Underground mine is fully permitted.”
Proven Reservepositive
Measured Resource with demonstrated economic viability after applying modifying factors.
Why it applies: The study reports Proven Mineral Reserves of 80,600 oz Au.
Evidence · table
“80.6”
Context: Total
Probable Reservepositive
Indicated Resource with demonstrated economic viability after applying modifying factors.
Why it applies: The study reports Probable Mineral Reserves of 475,900 oz Au.
Evidence · table
“475.9”
Context: Total
Measured Resourcepositive
Highest confidence category — tonnage, grade, shape well-established from closely-spaced drilling. Basis for Proven Reserves.
Why it applies: The study reports Measured Mineral Resources of 145,900 oz Au.
Evidence · table
“145.9”
Context: Total
Indicated Resourcepositive
Reasonable geological confidence based on adequate drilling; continuity can be assumed. Basis for Probable Reserves.
Why it applies: The study reports Indicated Mineral Resources of 713,600 oz Au.
Evidence · table
“713.6”
Context: Total
Inferred Resourcenegative
Speculative category — limited drilling, geological continuity assumed but not confirmed. Cannot support economic studies alone.
Why it applies: The study reports Inferred Mineral Resources of 202,800 oz Au.
Evidence · table
“202.8”
Context: Total
Category Upgradepositive
Resource confidence improved — Inferred upgraded to Indicated, or Indicated to Measured. De-risking signal.
Why it applies: Measured and Indicated underground Mineral Resources increased by 229%, and Inferred Mineral Resources decreased by 38% as material was converted into higher classification categories.
Evidence · text
“Measured and Indicated underground Mineral Resources increased by 229% to 3.73 Mt grading 7.17 g/t Au containing 859,500 oz Au, compared to the PEA(1); Inferred Mineral Resources decreased by 38% to 0.89 Mt grading 7.06 g/t Au containing 202,800 oz Au as the infill program converted a portion of Inferred Mineral Resources into the higher classification categories.”
Contained Metal Growthpositive
True scale improvement — contained metal ounces/tonnes increased vs prior, accounting for both tonnage and grade changes.
Why it applies: Approximately 65,000 ounces have been added to mineral inventory compared to the PEA, after accounting for mining depletion.
Evidence · text
“approximately 65,000 ounces have been added to mineral inventory (see Figures 1 and 2).”
QP/CP Signedpositive
Qualified Person (QP) or Competent Person (CP) named and signed off — a member of a recognized professional association (e.g., AusIMM, SME, AIG, P.Geo) with relevant experience.
Why it applies: Mineral Reserves were estimated by Anton Chan, P.Eng, MMSAQP, and Mineral Resources by Benjamin Parsons, MAusIMM (CP), both Qualified Persons under NI 43-101 and S-K 1300.
Evidence · text
“The Mineral Reserves were estimated by Anton Chan, B.Eng, M.Sc., P.Eng, MMSAQP(#01546QP) of SRKConsulting, U.S. (Inc.), a Qualified Person under NI 43-101 and S-K 1300.”
NI 43-101 Compliantpositive
Resource estimate prepared in compliance with NI 43-101 (Canada) — high reporting standard.
Why it applies: The technical report is prepared under National Instrument 43-101.
Evidence · text
“a technical report prepared under National Instrument 43-101 – Standards of Disclosure for Mineral Projects ("NI 43-101")”
Refractory Orenegative · Story-specific tag
Ore requires oxidation/pressure treatment before recovery — a processing and recovery risk.
Why it applies: Metallurgical testing demonstrated that the ore contains predominantly single refractory material requiring oxidation.
Evidence · text
“Metallurgical testing has demonstrated that the Ogee, Otto and South Pacific zones at Granite Creek Underground contain predominantly single refractory material and require an oxidation process to increase gold extraction using cyanidation.”
Mill Routeneutral · Story-specific tag
Processing via mill or concentrator (CIL, CIP, tank leach, flotation).
Why it applies: The processing strategy involves the Lone Tree autoclave and carbon-in-leach (CIL) plant.
Evidence · text
“Lone Tree autoclave and carbon-in-leach plant”
POX/BIOX Routeneutral · Story-specific tag
Pressure or bio-oxidation for refractory ore — high CAPEX and OPEX.
Why it applies: The ore requires an oxidation process, specifically acid pressure oxidation (POX) conditions.
Evidence · text
“acidic autoclave environment achieved higher sulfide oxidation and superior gold recovery rates. These results confirm that the Project's ore can be processed via the Lone Tree Plant's acid pressure oxidation ("POX") conditions”
Cut-off Disclosedpositive
Cut-off grade used for resource reporting is clearly stated, enabling like-for-like comparison.
Why it applies: A current resource fact retains the disclosed cut-off grade
Resource Updateneutral
Revised estimate for an existing resource — compare to prior to assess progress.
Why it applies: The source explicitly discloses a revised resource estimate
Evidence · text
“Updated Mineral Resource Estimate”
Gravity Routeneutral
Gravity separation forms a material part of the flowsheet.
Why it applies: the document describes a gravity route ("gravity")
Multi-Domain Testedpositive
Variability across ore domains (oxide, transition, fresh) has been addressed.
Why it applies: 2 distinct composites were tested
Extracted facts
Stored fact records: 6. Some facts used in scoring do not have a stored record.
Resource Estimates (4)
provenGranite Creek Underground · goldTonnes: 40000Grade: 11.21Grade Unit: g/tContained Metal: 14.5Contained Unit: kozView all detailsHide details
Identity
- Project
- Granite Creek Underground
- Commodity
- gold
- Region
- usa_nv
- Reported Region
- Nevada, USA
- Ticker
- IAU.TO
Resource scope
- Estimate type
- reserve
- Effective date
- 2026-03-31T00:00:00.000Z
- Reporting standards
- ni_43_101, sec_sk1300
- QP Signed
- Yes
- Qualified person names
- Anton Chan
- Resource group id
- resource:e321a02050188aea355d
- Deposit or zone
- South Pacific
- Mining method
- underground
- Ownership percent
- 100 %
- Resource basis
- attributable
Resource Data
- Category
- proven
- Tonnes
- 40000
- Grade
- 11.21
- Grade Unit
- g/t
- Contained Metal
- 14.5
- Contained Unit
- koz
- Cutoff Grade
- 4.42
- Cutoff Unit
- g/t
Prior Estimate
- Resource Date
- 2026-03-31
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-09-21T00:00:00.000Z
Reasoning: The Proven Reserve of 14.5 koz Au at 11.21 g/t in the South Pacific zone represents a very high-grade component of the initial reserve estimate, indicating strong confidence in this area. The estimate is NI 43-101 and S-K 1300 compliant with QP sign-off.
Positive factors
- Very high-grade Proven Reserve in the South Pacific zone
- QP signed off on the estimate
Tags used in scoring
Proven Reservepositive
Measured Resource with demonstrated economic viability after applying modifying factors.
Why it applies: category is "proven"
Cut-off Disclosedpositive
Cut-off grade used for resource reporting is clearly stated, enabling like-for-like comparison.
Why it applies: cutoff_grade is stated
QP/CP Signedpositive
Qualified Person (QP) or Competent Person (CP) named and signed off — a member of a recognized professional association (e.g., AusIMM, SME, AIG, P.Geo) with relevant experience.
Why it applies: qp_signed is true
NI 43-101 Compliantpositive
Resource estimate prepared in compliance with NI 43-101 (Canada) — high reporting standard.
Why it applies: reporting_standards includes ni_43_101
measuredGranite Creek Underground · goldTonnes: 65000Grade: 9.85Grade Unit: g/tContained Metal: 20.7Contained Unit: kozView all detailsHide details
Identity
- Project
- Granite Creek Underground
- Commodity
- gold
- Region
- usa_nv
- Reported Region
- Nevada, USA
- Ticker
- IAU.TO
Resource scope
- Estimate type
- resource
- Effective date
- 2026-03-31T00:00:00.000Z
- Reporting standards
- ni_43_101, sec_sk1300
- QP Signed
- Yes
- Qualified person names
- Benjamin Parsons
- Resource group id
- resource:a3f07c298becc85028ab
- Deposit or zone
- South Pacific
- Ownership percent
- 100 %
- Resource basis
- attributable
Resource Data
- Category
- measured
- Tonnes
- 65000
- Grade
- 9.85
- Grade Unit
- g/t
- Contained Metal
- 20.7
- Contained Unit
- koz
- Cutoff Grade
- 3.75
- Cutoff Unit
- g/t
Prior Estimate
- Resource Date
- 2026-03-31
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-09-21T00:00:00.000Z
Reasoning: The Measured Resource of 20.7 koz Au at 9.85 g/t in the South Pacific zone represents a very high-grade component of the updated resource estimate, indicating strong confidence. The estimate is compliant with major reporting standards and has QP sign-off.
Positive factors
- Very high-grade Measured Resource in the South Pacific zone
- QP signed off on the estimate
- Compliant with NI 43-101 and S-K 1300 reporting standards
Tags used in scoring
Measured Resourcepositive
Highest confidence category — tonnage, grade, shape well-established from closely-spaced drilling. Basis for Proven Reserves.
Why it applies: category is "measured"
Cut-off Disclosedpositive
Cut-off grade used for resource reporting is clearly stated, enabling like-for-like comparison.
Why it applies: cutoff_grade is stated
QP/CP Signedpositive
Qualified Person (QP) or Competent Person (CP) named and signed off — a member of a recognized professional association (e.g., AusIMM, SME, AIG, P.Geo) with relevant experience.
Why it applies: qp_signed is true
NI 43-101 Compliantpositive
Resource estimate prepared in compliance with NI 43-101 (Canada) — high reporting standard.
Why it applies: reporting_standards includes ni_43_101
indicatedGranite Creek open pit · goldGrade: 0.97Grade Unit: g/tContained Metal: 1591000Contained Unit: ozView all detailsHide details
Identity
- Project
- Granite Creek open pit
- Commodity
- gold
- Region
- usa_nv
- Reported Region
- Nevada, USA
- Ticker
- IAU.TO
Resource scope
- Estimate type
- resource
- Reporting standards
- ni_43_101, sec_sk1300
- QP Signed
- Yes
- Qualified person names
- Benjamin Parsons
- Resource group id
- resource:4a9cd81151d1b965de34
- Mining method
- open_pit
- Ownership percent
- 100 %
- Resource basis
- attributable
Resource Data
- Category
- indicated
- Grade
- 0.97
- Grade Unit
- g/t
- Contained Metal
- 1591000
- Contained Unit
- oz
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-09-21T00:00:00.000Z
Reasoning: The updated open pit resource estimate shows a substantial Measured and Indicated resource of 1,591,000 oz Au at 0.97 g/t Au, representing an 11% increase from the prior PEA. This provides significant future potential, although it is not yet converted to reserves and requires further studies and permitting. The estimate is compliant with major reporting standards and has QP sign-off.
Positive factors
- Large Measured and Indicated open pit resource of 1,591,000 oz Au
- QP signed off on the estimate
- Compliant with NI 43-101 and S-K 1300 reporting standards
- Measured and Indicated resources increased by 11% compared to PEA
Negative factors
- No reserves for the open pit portion
- Still subject to ongoing technical studies and permitting activities
Tags used in scoring
Indicated Resourcepositive
Reasonable geological confidence based on adequate drilling; continuity can be assumed. Basis for Probable Reserves.
Why it applies: category is "indicated"
Cut-off Undisclosednegative
High-grade interval reported without stating the cut-off grade used for compositing.
Why it applies: no cutoff_grade was stated
QP/CP Signedpositive
Qualified Person (QP) or Competent Person (CP) named and signed off — a member of a recognized professional association (e.g., AusIMM, SME, AIG, P.Geo) with relevant experience.
Why it applies: qp_signed is true
NI 43-101 Compliantpositive
Resource estimate prepared in compliance with NI 43-101 (Canada) — high reporting standard.
Why it applies: reporting_standards includes ni_43_101
inferredGranite Creek open pit · goldGrade: 0.81Grade Unit: g/tContained Metal: 99800Contained Unit: ozView all detailsHide details
Identity
- Project
- Granite Creek open pit
- Commodity
- gold
- Region
- usa_nv
- Reported Region
- Nevada, USA
- Ticker
- IAU.TO
Resource scope
- Estimate type
- resource
- Reporting standards
- ni_43_101, sec_sk1300
- QP Signed
- Yes
- Qualified person names
- Benjamin Parsons
- Resource group id
- resource:b0bfd61556ad52cf8879
- Mining method
- open_pit
- Ownership percent
- 100 %
- Resource basis
- attributable
Resource Data
- Category
- inferred
- Grade
- 0.81
- Grade Unit
- g/t
- Contained Metal
- 99800
- Contained Unit
- oz
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-09-21T00:00:00.000Z
Reasoning: The updated open pit resource estimate includes 99,800 oz Au at 0.81 g/t Au in the Inferred category, representing a 33% increase from the prior PEA. While this indicates potential, it carries lower geological confidence and requires further work for conversion to higher categories and reserves. The estimate is compliant with major reporting standards and has QP sign-off.
Positive factors
- QP signed off on the estimate
- Compliant with NI 43-101 and S-K 1300 reporting standards
- Inferred resources increased by 33% compared to PEA
Negative factors
- Inferred category has lower geological confidence
- No reserves for the open pit portion
- Still subject to ongoing technical studies and permitting activities
Tags used in scoring
Inferred Resourcenegative
Speculative category — limited drilling, geological continuity assumed but not confirmed. Cannot support economic studies alone.
Why it applies: category is "inferred"
Cut-off Undisclosednegative
High-grade interval reported without stating the cut-off grade used for compositing.
Why it applies: no cutoff_grade was stated
QP/CP Signedpositive
Qualified Person (QP) or Competent Person (CP) named and signed off — a member of a recognized professional association (e.g., AusIMM, SME, AIG, P.Geo) with relevant experience.
Why it applies: qp_signed is true
NI 43-101 Compliantpositive
Resource estimate prepared in compliance with NI 43-101 (Canada) — high reporting standard.
Why it applies: reporting_standards includes ni_43_101
Metallurgical Results (2)
metallurgical testingGranite Creek Underground · goldRecovery: 87 %View all detailsHide details
Identity
- Project
- Granite Creek Underground
- Commodity
- gold
- Region
- usa_nv
- Reported Region
- Nevada, USA
- Ticker
- IAU.TO
Test Work
- Program Status
- detailed
- Test Type
- metallurgical testing
- Processing Route
- acid pressure oxidation (POX) and carbon-in-leach (CIL)
- Sample
- Ogee, Otto and South Pacific zones
Recovery
- Recovery
- 87 %
- Recovery Basis
- actual_test
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-09-21T00:00:00.000Z
Reasoning: Metallurgical testing confirmed an average gold recovery of 87% for the refractory ore from the Ogee, Otto, and South Pacific zones using an acidic autoclave environment. This is a strong recovery for refractory material and confirms the suitability of the Lone Tree Plant's POX circuit. The refractory nature of the ore is a processing challenge but is addressed by the chosen flowsheet.
Positive factors
- High average gold recovery of 87% for refractory ore
- Acidic autoclave environment achieved superior gold recovery rates
- Processing via Lone Tree Plant's POX conditions confirmed
Negative factors
- Ore is predominantly single refractory material, requiring oxidation
Tags used in scoring
Mill Routeneutral
Processing via mill or concentrator (CIL, CIP, tank leach, flotation).
Why it applies: processing_route matches the mill_cil signal
POX/BIOX Routeneutral
Pressure or bio-oxidation for refractory ore — high CAPEX and OPEX.
Why it applies: processing_route matches the pox_biox signal
metallurgical testingGranite Creek Underground · goldRecovery: 69 %Head Grade: 10.02Head Grade Unit: g/tView all detailsHide details
Identity
- Project
- Granite Creek Underground
- Commodity
- gold
- Region
- usa_nv
- Reported Region
- Nevada, USA
- Ticker
- IAU.TO
Test Work
- Program Status
- detailed
- Test Type
- metallurgical testing
- Processing Route
- carbon-in-leach (CIL)
- Sample
- Oxide mineralization in Ogee Zone
Recovery
- Recovery
- 69 %
- Recovery Basis
- actual_test
- Head Grade
- 10.02
- Head Grade Unit
- g/t
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-09-21T00:00:00.000Z
Reasoning: The oxide mineralization, primarily from the Ogee Zone, shows a gold payability/recovery of 69% and can be processed directly through the Lone Tree Plant's CIL circuit, bypassing the more complex POX circuit. While the recovery is lower than for refractory ore, this simplified processing route offers lower operating costs. The FS only incorporates a small component of oxide mineralization, suggesting potential for future optimization.
Positive factors
- Oxide ore can be processed directly by CIL circuit, bypassing POX
- Lower overall operating costs for oxide processing
Negative factors
- Lower gold payability/recovery for oxide ore (69%) compared to refractory (87%)
Tags used in scoring
Mill Routeneutral
Processing via mill or concentrator (CIL, CIP, tank leach, flotation).
Why it applies: processing_route matches the mill_cil signal
Low Recoverynegative
Recovery below the weak band for the commodity and processing route.
Why it applies: 69% is below the weak band (80%)
How Atlas produces this analysis
Minestarters Atlas uses automated extraction to summarize mining announcements, identify reported measurements, and classify supporting evidence. Sentiment reflects the extracted narrative and classification rules; it is an interpretation, not a reported measurement. Evidence quotes and context are provided where available. Missing data, low-confidence results, and review flags indicate limitations. Check the original publisher announcement before relying on an interpretation.