I-80’s Granite Creek resources triple, costs jump
Original announcement by northernminer on
- Company
- i-80 Gold
- Ticker
- IAU
- Exchange
- Unavailable
- Region
- Nevada
- Primary commodity
- Gold
- Secondary commodities
- None reported
- Document categories
- Resource update, Economic study
- Extracted
- 2026-09-22 14:49:29 UTC
Analysis by Minestarters Atlas
Minestarters Atlas analysis
Summary
i-80 Gold has released a new feasibility study for the Granite Creek underground mine in Nevada, reporting a 229% increase in measured and indicated resources to 859,500 oz and the establishment of 556,500 oz of initial reserves. However, the study highlights a significant increase in life-of-mine AISC to $2,273/oz, up from $1,597/oz in the previous PEA.
Reasoning: The announcement delivers a major resource expansion and reserve establishment via a new feasibility study, but the economic profile is tempered by a significant jump in life-of-mine AISC.
Positive factors
- Significant resource growth (229% increase in M&I)
- Establishment of initial reserves
- Improved metallurgical recovery (87% vs 78%)
- Expansion of mineralized footprint
Negative factors
- Sharply higher AISC ($2,273 vs $1,597 in PEA)
- NPV sensitivity shows value erosion at higher gold prices compared to prior study
- Elevated costs weighting the economics
Facts used in scoring: 3
Classification and evidence
PFS Completepositive
AACE Class 3 study complete.
Why it applies: The document describes a new feasibility study which, in the context of the project stage, serves as the primary economic update.
Evidence · text
“a new feasibility study also shows sharply higher costs than last year’s preliminary assessment”
Category Upgradepositive
Resource confidence improved — Inferred upgraded to Indicated, or Indicated to Measured. De-risking signal.
Why it applies: The study establishes initial reserves and lifts measured and indicated resources significantly.
Evidence · text
“It also establishes initial reserves of 556,500 oz. and lifts measured and indicated resources 229% to 859,500 ounces.”
Tonnage Growthpositive
Tonnage increase reaching the strong tier vs prior estimate, with grade maintained or improved.
Why it applies: Measured and indicated resources increased by 229% compared to the previous PEA.
Evidence · text
“lifts measured and indicated resources 229% to 859,500 ounces”
Grade Declinenegative
Average grade fell below the red-flag bound vs prior estimate — deposit economics worsening. May indicate high-grading in early drilling.
Why it applies: While not explicitly stated as a decline, the massive tonnage growth relative to metal growth suggests dilution or lower grade expansion, though the headline grade remains high.
Evidence · text
“lifts measured and indicated resources 229% to 859,500 ounces”
Extracted facts
Stored fact records: 3. Some facts used in scoring do not have a stored record.
Resource Estimates (3)
probableGranite Creek · goldTonnes: 2200000Grade: 7.87Grade Unit: g/tContained Metal: 556500Contained Unit: ozView all detailsHide details
Identity
- Project
- Granite Creek
- Commodity
- gold
- Region
- usa_nv
- Reported Region
- Nevada
- Ticker
- IAU
Resource scope
- Estimate type
- reserve
- Resource group id
- resource:469f995a576a3676ad2e
- Mining method
- combined
Resource Data
- Category
- probable
- Tonnes
- 2200000
- Grade
- 7.87
- Grade Unit
- g/t
- Contained Metal
- 556500
- Contained Unit
- oz
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-09-22T00:00:00.000Z
Reasoning: First formal reserve declaration for the project.
Positive factors
- Establishes initial reserves
Evidence · text
“The study establishes an initial 2.2 million proven and probable tonnes grading 7.87 grams gold per tonne for 556,500 oz. contained gold.”
Tags used in scoring
Probable Reservepositive
Indicated Resource with demonstrated economic viability after applying modifying factors.
Why it applies: category is "probable"
Cut-off Undisclosednegative
High-grade interval reported without stating the cut-off grade used for compositing.
Why it applies: no cutoff_grade was stated
No QP/CP Disclosurenegative
No Qualified Person or Competent Person named — lower credibility for the estimate. A QP/CP should be a member of a recognized professional association with relevant experience.
Why it applies: no Qualified or Competent Person is named anywhere in the release
PEA-Supportingneutral
Resource estimate prepared to support a Preliminary Economic Assessment — early-stage study.
Why it applies: the release names the study this estimate supports
DFS-Supportingneutral
Resource estimate prepared to support a Definitive Feasibility Study — requires high M&I confidence.
Why it applies: the release names the study this estimate supports
indicatedGranite Creek · goldTonnes: 3730000Grade: 7.17Grade Unit: g/tContained Metal: 859500Contained Unit: ozView all detailsHide details
Identity
- Project
- Granite Creek
- Commodity
- gold
- Region
- usa_nv
- Reported Region
- Nevada
- Ticker
- IAU
Resource scope
- Estimate type
- resource
- Resource group id
- resource:cbd567dd6c98d0618cdf
- Mining method
- combined
Resource Data
- Category
- indicated
- Tonnes
- 3730000
- Grade
- 7.17
- Grade Unit
- g/t
- Contained Metal
- 859500
- Contained Unit
- oz
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-09-22T00:00:00.000Z
Reasoning: Significant increase in M&I resource scale.
Positive factors
- Substantial resource growth
Evidence · text
“Granite Creek now hosts 3.73 million measured and indicated tonnes grading 7.17 grams gold per tonne for 859,500 oz., up 229% from the PEA”
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
No QP/CP Disclosurenegative
No Qualified Person or Competent Person named — lower credibility for the estimate. A QP/CP should be a member of a recognized professional association with relevant experience.
Why it applies: no Qualified or Competent Person is named anywhere in the release
PEA-Supportingneutral
Resource estimate prepared to support a Preliminary Economic Assessment — early-stage study.
Why it applies: the release names the study this estimate supports
DFS-Supportingneutral
Resource estimate prepared to support a Definitive Feasibility Study — requires high M&I confidence.
Why it applies: the release names the study this estimate supports
inferredGranite Creek · goldTonnes: 893000Grade: 7.06Grade Unit: g/tContained Metal: 202800Contained Unit: ozView all detailsHide details
Identity
- Project
- Granite Creek
- Commodity
- gold
- Region
- usa_nv
- Reported Region
- Nevada
- Ticker
- IAU
Resource scope
- Estimate type
- resource
- Resource group id
- resource:fd35a0011067b49a6251
- Mining method
- combined
Resource Data
- Category
- inferred
- Tonnes
- 893000
- Grade
- 7.06
- Grade Unit
- g/t
- Contained Metal
- 202800
- Contained Unit
- oz
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-09-22T00:00:00.000Z
Reasoning: Inferred resource is present but smaller than before due to conversion to higher confidence categories.
Positive factors
- Maintains high grade in inferred category
Negative factors
- Inferred ounces declined due to conversion
Evidence · text
“while 893,000 inferred tonnes grade 7.06 grams for 202,800 ounces.”
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
No QP/CP Disclosurenegative
No Qualified Person or Competent Person named — lower credibility for the estimate. A QP/CP should be a member of a recognized professional association with relevant experience.
Why it applies: no Qualified or Competent Person is named anywhere in the release
PEA-Supportingneutral
Resource estimate prepared to support a Preliminary Economic Assessment — early-stage study.
Why it applies: the release names the study this estimate supports
DFS-Supportingneutral
Resource estimate prepared to support a Definitive Feasibility Study — requires high M&I confidence.
Why it applies: the release names the study this estimate supports
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.