Stibnite Gold-Antimony Project by Perpetua Resources: status and timeline

Stibnite Gold-Antimony Project

Give the US a domestic antimony supply for munitions, batteries and industry after China cut exports, while producing about 300,000 oz of gold a year to pay for it.

PilotStage 3 of 5

Early construction since Oct 2025; $2.9B EXIM loan to close and final decision due Q4 2026.

Updated 31 Aug 2026Checked 11 Oct0 updates this week

Milestones

Next · EXIM loan closes; final investment decision

US Forest Service Record of Decision approves mine plan3 Jan 2025Complete.
Early works construction beginsOct 2025Complete.
EXIM board approves $2.9B loan21 May 2026Complete.
Antimony trisulfide plant opens at Idaho National Laboratory29 Jul 2026Complete.
US District Court affirms federal approvals18 Aug 2026Complete.
EXIM loan closes; final investment decisionTarget Q4 2026Current milestone.
First production after about three years of constructionTarget 2029Not yet reached.

Most important updates

Upcoming

Q4 2026EXIM loan closes; final investment decision (next)
2029First production after about three years of construction

Current obstacles

Financing must close firstFull construction waits for the $2.9B EXIM loan to close and a final investment decision, both expected in Q4 2026.
Ongoing legal challengesCourts refused an injunction (May 2026), upheld the air permit (July) and affirmed federal approvals (August); an appeal is still pending.
Where to refine the antimonyThe US lacks large antimony refining; Perpetua is still choosing outside processors for its concentrate.

Physics limits

Geology sets the gradeHow much metal each tonne of rock holds is fixed by the deposit. Lower grades mean more rock moved, energy used and waste stored per kilo of product.
Sulfide ores need energy to unlockGold and antimony here sit in sulfide minerals. Breaking them apart takes high heat and pressure or roasting, which costs energy and creates sulfur that must be managed.
A deposit runs outA mine is a finite resource: Stibnite's reserve supports about 15 years, so long-term supply needs new discoveries or recycling.

How it works

4 parts

Mine

Open pits on a WWII-era site

Ore is dug from open pits at Stibnite, which supplied about 90% of US antimony during World War II. The plan also cleans up waste left by earlier mining.

Antimony

Antimony split off first

High-antimony ore goes through selective flotation: antimony minerals cling to air bubbles and float off as a concentrate shipped for refining.

Gold

Pressure oxidation frees the gold

Gold sits inside sulfide minerals. An autoclave at about 220 °C with pressurised oxygen breaks them down so the gold can be leached out.

Defence

Munitions-grade product

A pilot plant at Idaho National Laboratory turns Stibnite antimony samples into antimony trisulfide, used in ammunition, for Army qualification.

Spec sheet

Spec	Stibnite Gold-Antimony Project
Antimony reserve	148 million lb^R (reported)
Share of US antimony demand	~35% (first six years)^R (reported)
Gold reserve	4.8 million oz^R (reported)
Average gold output	~300,000 oz/year^R (reported)
Mine life	15 years^R (reported)
Initial capital cost	$2.58B^R (reported)
EXIM loan	$2.9B^R (reported)
Jobs (construction / operations)	~950 / ~550^R (reported)

^R reported by the company

Update log

3 updates

About Perpetua Resources

The team behind Stibnite Gold-Antimony Project

Perpetua Resources

Stibnite gold-antimony mine, Idaho

Perpetua Resources is developing the Stibnite Gold Project in central Idaho, a former mine that holds the only identified antimony reserve in the US. Gold pays for the mine; antimony, used in munitions and other defence goods, is the strategic prize.

Stibnite holds 148 million lb of antimony, expected to meet about 35% of US demand in its first six years.
US EXIM approved a $2.9B loan in May 2026; closing and a final build decision are expected in Q4 2026.
Over $87M of US defence awards since 2022, including an antimony trisulfide pilot plant at Idaho National Laboratory.

perpetuaresources.com (opens perpetuaresources.com)Company profile →

Headquarters: United States
Status: Public
Listed: PPTA
Valuation: public
Raised: $255M1 round
Last round: Private placement · $255MOct 2025
Works in: MaterialsLithium & critical minerals
Coverage: 1 program · 4 updateslatest 31 Aug 2026checked 11 Oct
Lead investors: Agnico Eagle MinesJPMorgan Chase
Partners: US Army (opens perpetuaresources.com)Idaho National Laboratory (opens inl.gov)
Investors: Agnico Eagle Mines (opens agnicoeagle.com)JPMorgan Chase (opens jpmorganchase.com)Export-Import Bank of the United States (opens exim.gov)
People: Jon CherryCEO

Spec

Stibnite Gold-Antimony Project

Antimony reserve

148 million lb^R (reported)

Share of US antimony demand

~35% (first six years)^R (reported)

Gold reserve

4.8 million oz^R (reported)

Average gold output

~300,000 oz/year^R (reported)

Mine life

15 years^R (reported)

Initial capital cost

$2.58B^R (reported)

EXIM loan

$2.9B^R (reported)

Jobs (construction / operations)

~950 / ~550^R (reported)

Stibnite Gold-Antimony Project

Milestones

Most important updates

Upcoming

Current obstacles

Physics limits

How it works

Open pits on a WWII-era site

Antimony split off first

Pressure oxidation frees the gold

Munitions-grade product

Spec sheet

Update log

Mon 31 Aug

Thu 21 May

Wed 22 Oct 2025

About Perpetua Resources

Current obstacles

Physics limits

How it works

Open pits on a WWII-era site

Antimony split off first

Pressure oxidation frees the gold

Munitions-grade product

Spec sheet

Update log

Mon 31 Aug

Thu 21 May

Wed 22 Oct 2025

About Perpetua Resources