Endeavour Mining Backs Altair Minerals’ Greater Oko Gold Project Guyana

A Top-10 Global Gold Producer Just Backed This Junior Explorer at a Premium — Here's Why It Matters

Altair Minerals Limited (ASX: ALR) has secured a $28.2 million strategic placement from Endeavour Gold Corporation, a wholly owned subsidiary of Endeavour Mining plc (LSE/TSX: EDV) — the largest gold producer in West Africa and a top-10 senior gold producer globally. The Altair Minerals Endeavour Mining strategic placement for the Greater Oko gold project Guyana represents a deal struck at a 5% premium to Altair's last closing price, a 40% premium to its 30-day VWAP, and an 11% premium to its 5-day VWAP — a rare and emphatic vote of confidence in a junior explorer.

Upon completion, Endeavour will hold a 9.90% stake in Altair, becoming its largest strategic shareholder. The capital injection lifts Altair's pro-forma treasury to approximately $40 million, providing the firepower to dramatically scale exploration across the Greater Oko Project in Guyana — what the company describes as the largest consolidated gold exploration project in the country at 428 km².

"Endeavour's investment into Altair, given their technical expertise in greenstone belt exploration, is a strong endorsement of the prospectivity and scalability of Altair's land package… Greater Oko remains the last untapped 'Birimian-Like' greenstone belt on the planet, sitting in a pro-mining and politically stable jurisdiction." — CEO Faheem Ahmed

This is not a routine capital raise. This is a major mining house — one with 22.4 million ounces of Measured & Indicated gold discoveries since 2016 — making a deliberate, above-market bet on a junior with a consolidated land position in one of the world's most under-explored gold provinces.

What the Placement Means in Numbers

The placement is structured in two tranches:

1. Tranche 1 — 398,000,000 shares, settling 30 April 2026, with allotment and normal trading from 1 May 2026
2. Tranche 2 — 258,264,364 shares, subject to shareholder approval at an EGM scheduled for mid-June 2026, with settlement and trading to follow shortly after

62 Capital Pty Ltd and Argonaut Securities Pty Limited acted as Joint Lead Managers to the Placement.

Understanding the Greenstone Belt Connection — Why Does This Geology Matter?

What Is a Birimian Greenstone Belt?

Greenstone belts are ancient volcanic and sedimentary rock sequences that are among the most productive geological environments for gold mineralisation on Earth. The West African Birimian Greenstone Belt is one of the world's premier gold-producing geological provinces — it hosts many of Endeavour Mining's key assets and has been the source of the company's extraordinary track record of discovery.

The critical insight underpinning Altair's investment thesis is geological: the Guiana Shield in South America is widely regarded as a geological continuation of the West African Birimian system — essentially the same ancient crustal architecture, separated over geological time by the opening of the Atlantic Ocean.

Why Does This Matter to Investors?

• The West African Birimian belt has been extensively explored and has yielded multiple multi-million-ounce gold deposits
• The Guiana Shield equivalent remains, by comparison, significantly under-explored
• Endeavour's team has direct, hands-on expertise in Birimian-style mineralisation — and they are now strategically aligned with Altair to apply that knowledge at Greater Oko
• This geological continuity is not a theoretical concept; it is the core commercial rationale behind Endeavour's investment

In simple terms, the same geology that made Endeavour one of the world's great gold finders is what Altair is sitting on — and now Endeavour has a seat at the table.

How Will the $28.2 Million Be Deployed?

The placement proceeds have been allocated across five clear strategic priorities, with an immediate focus on scaling activity at Greater Oko.

1. Expanding the Drill Program — ~66% Increase

• Total program scaled to an anticipated 50,000m (up from the current maiden program)
• Comprising 25,000m Diamond and 25,000m RAB drilling
• A minimum of 15,000m diamond and 15,000m RAB allocated specifically to South Oko

2. Accelerating Drilling — More Rigs, Faster Results

• A second RAB rig to be immediately secured, enabling simultaneous drilling at both North Peters and South Oko targets
• Upon exploration success at virgin diamond targets, Altair retains the optionality to bring an additional two to four diamond drill rigs to rapidly delineate any mineralised zone

3. Doubling Geochemical Programs at South Oko

• Additional geochemical personnel, sampling tools, and rods deployed immediately
• Second excavator to be procured to double the rate of trenching
• Accommodation facilities and logistics at South Oko to be expanded to underpin long-term programme acceleration

4. Regional Targeting Programmes

• Two additional ATVs to be secured and new access routes established for regional geochemical and prospecting programmes
• Initial focus on prospective parallel shear targets surrounding South Oko
• Desktop studies to commence on regional target areas with documented historical gold production — currently completely untested

5. Long-Term Exploration Optionality — Phase II Capability

• The ~$40 million pro-forma balance provides runway for systematic multi-target drill testing
• Positions Altair to fund a potential Phase II diamond programme of >30,000m should a major discovery emerge
• Supports the ability to advance multiple discoveries in parallel and sustain a multi-year target pipeline

The Strategic Alliance — More Than Just Capital

What separates this placement from a standard capital raise is the operational and technical partnership embedded within it. Both parties have agreed to establish a joint Technical Committee to leverage key exploration synergies.

Critically, the parties can mutually elect Sonia Scarselli — Endeavour's Executive Vice President of Exploration, formerly BHP's Vice President of Exploration — to serve as Special Advisor to the Board and the Greater Oko Project. This is an exceptional calibre of technical expertise being directed toward Altair's asset.

Furthermore, this alignment creates a strategic dynamic that capital alone cannot replicate:

Endeavour's exploration methodology — described as a "bespoke" systematic approach — is what has driven its discovery success across West Africa. Consequently, the opportunity to apply that same framework to the Guiana Shield is what makes this relationship strategically differentiated.

Greater Oko: The Asset Underpinning the Investment Case

Greater Oko sits in Guyana — a jurisdiction that has drawn increasing interest from major mining firms globally. The project currently spans 428 km² following a deliberate permit streamlining process, retaining its position as the largest contiguous gold exploration project in Guyana.

The permit structure in Guyana is notably fragmented, with most individual exploration blocks sitting at approximately 4 km² — making Altair's consolidated land position a genuine structural competitive advantage and a significant barrier to entry for would-be competitors.

Four key target areas have been defined to date, spanning 55 km across the project, with exploration at both North Peters and South Oko already delivering meaningful early-stage results referenced in prior announcements.

As part of an ongoing streamlining process, Altair relinquished a set of non-material permits back to the Vendor. These permits did not fall within Altair's 24-month exploration plans and have no impact on current targets or execution. In parallel, both Altair and the Vendor are actively working on adding higher-priority permits adjoining Greater Oko, ensuring the portfolio is concentrated on the most prospective ground.

Why Investors Should Be Paying Close Attention

The convergence of several factors makes this announcement materially significant for investors tracking Altair. Indeed, the Altair Minerals Endeavour Mining strategic placement for the Greater Oko gold project Guyana sends a powerful signal to the broader market:

• Premium-priced strategic investment from a top-10 global gold producer — at a 40% premium to the 30-day VWAP — signals that sophisticated mining capital has conducted detailed due diligence and arrived at a favourable conclusion on Greater Oko's potential
• $40 million treasury provides multi-year exploration runway without near-term dilution pressure, supporting an aggressive and sustained drill campaign
• Technical collaboration with one of the most decorated exploration teams in the gold sector, including access to Birimian Greenstone Belt expertise that is directly applicable to Greater Oko's geology
• First-mover advantage on the largest consolidated land position in Guyana, a jurisdiction attracting growing attention from major mining companies
• Immediate operational scale-up — drilling expansion, additional rigs, doubled geochemical programmes — translating the placement proceeds into newsflow-generating activity in the near term

However, perhaps most compelling of all are the tangible, near-term catalysts on the horizon:

Altair Minerals has positioned itself as a serious player in one of the world's most prospective and under-explored gold provinces, now backed by the capital and technical credibility of a global gold major. With a $40 million treasury, an aggressive 50,000m drill programme underway, and Endeavour's exploration pedigree behind it, the coming months at Greater Oko have the potential to be transformational. Investors watching junior gold explorers should have ALR firmly on their radar.

Glossary of Key Terms

What Is a Birimian Greenstone Belt?

A geological formation spanning West Africa, among the world's most gold-productive rock sequences, known for hosting significant gold deposits. The Guiana Shield is considered its geological equivalent in South America.

What Is RAB Drilling?

RAB Drilling (Rotary Air Blast) is a fast and cost-effective drilling method used to collect rock chip samples during early-stage exploration, typically used to identify mineralised zones before committing to diamond drilling.

What Is Diamond Drilling?

Diamond Drilling is a precision drilling technique using a diamond-tipped drill bit to extract intact core samples, allowing detailed geological and geochemical analysis of subsurface mineralisation.

What Does VWAP Mean?

VWAP (Volume Weighted Average Price) is the average price of a stock weighted by trading volume over a defined period. A placement above VWAP signals the investor paid a premium relative to recent market trading activity.

What Are Measured & Indicated Resources?

Measured & Indicated (M&I) Resources are resource classifications under standard mining codes reflecting increasing levels of geological confidence in a mineral estimate. M&I resources form the basis for feasibility studies and mine planning.

What Is a Greenstone Belt?

Greenstone Belts are ancient sequences of volcanic and sedimentary rocks that are highly prospective for gold, copper, and other mineral deposits. They are among the most significant geological settings for major gold discoveries globally.

Ready to Learn More About Altair Minerals and the Greater Oko Gold Project?

With a $28.2 million strategic placement from a top-10 global gold producer, a $40 million pro-forma treasury, and the largest consolidated gold exploration project in Guyana, Altair Minerals (ASX: ALR) is rapidly emerging as a compelling opportunity for investors tracking junior gold explorers. To explore the full investment case — including the Greater Oko Project, the strategic alliance with Endeavour Mining, and the upcoming exploration catalysts — visit the official Altair Minerals website at altairminerals.com.au.