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, Production
- Extracted
- 2026-09-22 14:51:46 UTC
Analysis by Minestarters Atlas
Atlas analysis published:
Minestarters Atlas analysis
Summary
i-80 Gold has released a feasibility study for the Granite Creek underground mine in Nevada, reporting a 229% increase in measured and indicated resources to 859,500 ounces. While the study establishes initial reserves and improves recovery rates, it also forecasts a 42% increase in life-of-mine all-in sustaining costs compared to the previous preliminary economic assessment.
Reasoning: The announcement reports a major resource expansion and reserve establishment, but these gains are offset by a significant increase in projected operating costs.
Positive factors
- Significant resource growth (229% increase in M&I)
- Establishment of initial reserves
- Improved average recovery (87% vs 78%)
- Expansion of mineralized zones and continuity demonstrated
Negative factors
- Sharply higher life-of-mine all-in sustaining costs (up 42%)
- NPV sensitivity shows lower value at higher gold prices compared to PEA
- Elevated capital and closure costs
Facts used in scoring: 3
Classification and evidence
Category Upgradepositive
Resource confidence improved — Inferred upgraded to Indicated, or Indicated to Measured. De-risking signal.
Why it applies: Inferred ounces declined as they were converted into higher-confidence measured and indicated categories.
Evidence · text
“Much of the decline in inferred ounces reflects conversion into higher-confidence categories.”
Resource Updateneutral
Revised estimate for an existing resource — compare to prior to assess progress.
Why it applies: The document provides a new feasibility study updating the previous preliminary economic assessment.
Evidence · text
“a new feasibility study also shows sharply higher costs than last year’s preliminary assessment.”
Extracted facts
Stored fact records: 3. Some facts used in scoring do not have a stored record.
Resource Estimates (3)
provenGranite Creek · goldTonnes: 2200000Grade: 7.87Grade Unit: g/tContained Metal: 556500Contained Unit: oz.View 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:11bd5df3669462e0ba47
- Deposit or zone
- Granite Creek
- Mining method
- combined
Resource Data
- Category
- proven
- 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: New reserve establishment is a major project milestone.
Positive factors
- Establishes initial reserves
Evidence · text
“establishes initial reserves of 556,500 oz. ... 2.2 million proven and probable tonnes grading 7.87 grams gold per tonne for 556,500 oz. contained gold”
Tags used in scoring
Proven Reservepositive
Measured Resource with demonstrated economic viability after applying modifying factors.
Why it applies: category is "proven"
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:f79efc615cec97547086
- Deposit or zone
- Granite Creek
- 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: Substantial resource growth significantly de-risks the project.
Positive factors
- 229% increase in M&I resources
Evidence · text
“lifts measured and indicated resources 229% to 859,500 ounces. ... 3.73 million measured and indicated tonnes grading 7.17 grams gold per tonne for 859,500 oz.”
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:0f97f965cdef348b787f
- Deposit or zone
- Granite Creek
- 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 significant but lower confidence; decline in ounces is due to conversion to higher categories.
Positive factors
- Maintains high grade in inferred category
Negative factors
- Decline in inferred ounces due to conversion
Evidence · text
“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.