Aldebaran PEA for the Altar Project Reports 48 Year Mine Life, After Tax NPV (8%) of US$2 Billion, and 20.5% IRR

2025-10-30

TSXV - TSX Venture Exchange · Copper · Gold · Silver · Molybdenum · Antimony · Lead · Iron · Zinc · Sulfur · Arsenic · Canada

VANCOUVER, British Columbia, Oct. 30, 2025 (GLOBE NEWSWIRE) -- Aldebaran Resources Inc. (“ Aldebaran ” or the “ Company ”) (TSX-V: ALDE, OTCQX: ADBRF) is pleased to announce the results of a Preliminary Economic Assessment (“PEA”), prepared in accordance with National Instrument 43-101 standards, for the Altar copper-gold project located in San Juan, Argentina. The base case scenario utilizes a 60,000 tonnes per day (“tpd”) concentrator, processing mineralized material from both open pit and underground sources. The results of the PEA are reported on a 100% basis, while Aldebaran owns an 80% interest in the project, with the remaining 20% held by Sibanye-Stillwater Ltd.

All dollar amounts referenced herein are in US dollars unless otherwise noted.

HIGHLIGHTS

Long life operation with significant production:

48-year mine life, including 3 years of construction First 20 years 1 : Average annual production of 121,445 tonnes copper equivalent 2 (“CuEq”) 108,579 tonnes copper (“Cu”), 43,199 ounces of gold (“Au”), and 570,217 ounces of silver (“Ag”)

First 30 years 1 : Average annual production of 116,294 tonnes CuEq 105,897 tonnes Cu, 33,866 ounces of Au, and 557,239 ounces of Ag

LOM: Average annual production of 101,413 tonnes CuEq 92,891 tonnes Cu, 27,020 ounces of Au, and 525,192 ounces of Ag

Robust economics with leverage to commodity prices:

Using base-case metal prices of $4.35/lb Cu, $2,500/oz Au, and $27/oz Ag, the project has an after-tax NPV (8%) of $2.0 billion, an IRR of 20.5% and a payback period of 4 years Total LOM gross revenue of $44.7 billion (before TC/RCs, payabilities and transport) and total LOM free cash flow of $10.7 billion Using spot prices of $5.00/lb Cu, $3,963/oz Au, and $47/oz Ag, the project has an after-tax NPV (8%) of $3.34 billion and an IRR of 28.0% 4

Attractive capital intensity:

Initial capex for the project is $1.59 billion Upfront capital is minimized by taking a staged approach to the tailings storage facility and underground construction

Capital intensity of $15,713/t of average annual CuEq metal produced 3 NPV @ 8% / Initial Capex ratio of 1.27x

Competitive cost profile:

Cash Costs (C1) of $1.71/lb payable Cu for the first 20 years 1 , $1.87/lb payable Cu for the first 30 years 1 , and $2.02/lb payable Cu for the LOM All in Sustaining Costs (“AISC”) of $2.25/lb payable Cu for the first 20 years 1 , $2.42/lb payable Cu for the first 30 years 1 , and $2.59/lb payable Cu for the LOM

Combined Open Pit and Underground Operation:

Production from the open pit pays back the initial capital, while development of the underground is ongoing Underground mining pulls forward better grade mineralization earlier in the mine life, to increase production and generate cash flow ~80% of the resources (by tonnage) in the mine plan are categorized as Measured and Indicated, with the remaining ~20% categorized as Inferred

John Black, Chief Executive Officer of Aldebaran, commented: “ _This PEA confirms that the Altar project has the potential to become a long-life, high-quality copper operation capable of generating substantial production and cash flow. Our objective was to define a mine plan that delivers a minimum of 100,000 tonnes of CuEq per year, while maintaining a compact operational footprint and a disciplined approach to capital. The results of this study clearly achieve those objectives and demonstrate that Altar is a technically and economically robust project. This PEA represents a major milestone for the Company and provides the foundation for our upcoming application for inclusion under Argentina’s RIGI investment framework. With the political environment in Argentina shifting toward pro-business and pro-development policies—as underscored by the recent mid-term election results—the timing for advancing a project of Altar’s scale could not be better. The country is positioning itself to emerge as a significant copper producer at a time when global demand for the metal continues to rise. In addition to the base case concentrator scenario, our collaboration with Nuton, a Rio Tinto venture, demonstrates Nuton ® Technology as a potentially viable processing alternative at Altar. Utilizing Nuton ® Technology, life-of-mine capital expenditure and operating costs were reduced, leading to higher life-of-mine free cash flow. When you combine the economic results with the ESG benefits of Nuton’s sulphide leaching technology, the Nuton case is quite compelling and warrants further evaluation. The next 12 to 18 months will be transformative for the Company, with multiple key catalysts—including a resource update, completion of the PFS, and the proposed Centauri Minerals spin-out—positioning us to unlock significant value for our shareholders. _”

Kevin B. Heather, Chief Geological Officer of Aldebaran, commented: “ _The PEA represents a significant milestone for the Altar project. In addition to achieving the goals John stated above, we were also focused on maximizing NPV and IRR, hence we elected to move forward with a mine plan that included a combination of open-pit and underground block caving. The block cave, commencing production after the open pit pays back the initial capital, allows us to pull forward higher-grade material in the mine plan and to maintain constant CuEq production numbers, while keeping throughput at 60,000 tpd. Moreover, it keeps the overall footprint of the operation smaller, which is a key consideration for development projects. Our approach to capital expenditures was to stage capital outlays where possible, to ensure initial capital expenditures were kept manageable. Where possible, capital was paid out of cash flow to present a more prudent and attractive development opportunity. We will now begin to shift our focus to the PFS, which will be the next step in de-risking the Altar project. To that end, our 2025/2026 field program is now underway, with most of the work focused on collecting the additional data necessary for the upcoming PFS. This includes additional infill drilling, geotechnical drilling, lab-based geotechnical stress and strain test work, Acid Based Accounting (ABA) test work, environmental monitoring, water wells, water balance studies, community engagement, and more. While this work is ongoing, we will also be exploring several opportunities that we have identified that could potentially unlock additional value from the Altar Project. _”

PEA Overview

When available, readers are encouraged to read the PEA in the Company’s technical report (“ Technical Report ”) prepared in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“ 43-101 ”) in its entirety, including all qualifications, assumptions and exclusions that relate to the PEA and mineral resource model. The Technical Report is intended to be read as a whole, and sections should not be read or relied upon out of context.

The PEA envisions a combination of open-pit and underground mining, followed by processing via a conventional copper flotation circuit having a nameplate processing capacity of 60,000 tonnes per day. This results in a mine life of 48 years with an average annual production of 102,742 CuEq tonnes for LOM, 116,539 tonnes CuEq for the first 30 years, and 121,748 CuEq tonnes for the first 20 years. Table 1 presents key operating and financial highlights from the PEA, using base study case assumptions of $4.35/lb Cu, $2,500/oz Au and $27/oz Ag. Figure 1 displays annual CuEq production for the LOM, while Figure 2 displays projected cash flows.

| Table 1. PEA Summary | | | | | Metric | Unit | Base Case | | | Mine Life (including construction) | Years | 48 | | | After Tax NPV - 8% | M USD | 2,009 | | | IRR (after tax) | % | 20.5% | | | Payback | Years | 4 | | | Averal annual production (LOM) | tonnes CuEq | 101,413 | | | Averal annual production (LOM) | M lbs CuEq | 224 | | | Averal annual production (years 1-30) | tonnes CuEq | 116,294 | | | Averal annual production (years 1-30) | M lbs CuEq | 256 | | | Averal annual production (years 1-20) | tonnes CuEq | 121,445 | | | Averal annual production (years 1-20) | M lbs CuEq | 268 | | | LOM Gross Revenue 5 | M USD | 44,738 | | | LOM Free Cash Flow | M USD | 10,632 | | | Initial capital | M USD | 1,593 | | | Capital Intensity | USD/tonne CuEq | 15,713 | | | NPV/Initial Capex | Ratio | 1.27 | | | Construction Period | Years | 3 | | | LOM capital | M USD | 5,651 | | | C1 Cash Costs (LOM) | USD/lb Cu Payable | 2.02 | | | C1 Cash Costs (years 1-30) | USD/lb Cu Payable | 1.87 | | | C1 Cash Costs (years 1-20) | USD/lb Cu Payable | 1.71 | | | AISC (LOM) | USD/lb Cu Payable | 2.59 | | | AISC (years 1-30) | USD/lb Cu Payable | 2.42 | | | AISC (years 1-20) | USD/lb Cu Payable | 2.25 | | | Throughput | tonnes per day | 60,000 | | | LOM Cu Recovery | % | 87.76% | | | LOM Au Recovery | % | 57.00% | | | LOM Ag Recovery | % | 50.00% | | | LOM Open pit strip ratio | waste/mineralized | 1.53 | | | LOM Open pit mineralized tonnes mined | M tonnes | 223 | | | LOM Open pit Cu grade | % | 0.44% | | | LOM Open pit Au grade | g/t | 0.07 | | | LOM Open pit Ag grade | g/t | 1.18 | | | LOM Block cave mineralized tonnes mined | M tonnes | 768 | | | LOM Block cave Cu grade | % | 0.50% | | | LOM Block cave Au grade | g/t | 0.07 | | | LOM Block cave Ag grade | g/t | 1.61 | | | LOM Recovered Cu | M lbs | 9,420 | | | LOM Recovered Au | M Oz's | 1.24 | | | LOM Recovered Ag | M Oz's | 24.16 | | | | | | |

Figure 1 – LOM CuEq Production and C1 Cash Costs

Figure 2 – Project Cash Flows

Mineral Resource Estimate

On November 25, 2024, the Company announced an updated mineral resource estimate (“MRE”) for the Altar project (see Table 2). The PEA is based on the MRE; however, the PEA production profile is based on a subset of the MRE, utilizing different metal prices, operating costs, and mining methods.

| Table 2. 2024 Altar Resource Estimate - $13.99 NSR Cut-off (0.24% CuEq) | | | | | | | | | | | | | Average Grade | Contained Metal | | | | | | | | | | Material Type | Category | Tonnes (000's) | Cu (%) | Au (g/t) | Ag (g/t) | Mo (ppm) | As (ppm) | Cu (M lbs) | Au (M Ozs) | Ag (M Ozs) | | Supergene | Measured | 121,884 | 0.55 | 0.08 | 1.07 | 21 | 289 | 1,475 | 0.3 | 4.2 | | Indicated | 80,007 | 0.36 | 0.06 | 0.93 | 19 | 123 | 639 | 0.2 | 2.4 | | | Total M&I | 201,891 | 0.47 | 0.07 | 1.01 | 20 | 223 | 2,114 | 0.5 | 6.6 | | | Inferred | 24,850 | 0.46 | 0.07 | 1.01 | 19 | 213 | 251 | 0.1 | 0.8 | | | Mixed | Measured | 109,510 | 0.38 | 0.07 | 1.22 | 23 | 192 | 913 | 0.2 | 4.3 | | Indicated | 19,208 | 0.32 | 0.06 | 1.11 | 23 | 139 | 136 | 0.0 | 0.7 | | | Total M&I | 128,718 | 0.37 | 0.07 | 1.20 | 23 | 184 | 1,049 | 0.3 | 5.0 | | | Inferred | 1,386 | 0.29 | 0.07 | 1.00 | 13 | 111 | 9 | 0.0 | 0.0 | | | Hypogene | Measured | 549,385 | 0.41 | 0.10 | 0.98 | 20 | 120 | 4,966 | 1.7 | 17.3 | | Indicated | 1,517,339 | 0.42 | 0.05 | 1.33 | 54 | 114 | 13,882 | 2.6 | 64.9 | | | Total M&I | 2,066,724 | 0.41 | 0.07 | 1.24 | 45 | 116 | 18,848 | 4.3 | 82.2 | | | Inferred | 1,189,513 | 0.37 | 0.04 | 1.26 | 46 | 96 | 9,572 | 1.6 | 48.2 | | | Total | Measured | 780,779 | 0.43 | 0.09 | 1.03 | 21 | 156 | 7,354 | 2.3 | 25.8 | | Indicated | 1,616,554 | 0.41 | 0.05 | 1.31 | 52 | 115 | 14,657 | 2.8 | 68.0 | | | Total M&I | 2,397,333 | 0.42 | 0.07 | 1.22 | 42 | 128 | 22,011 | 5.1 | 93.8 | | | Inferred | 1,215,749 | 0.37 | 0.04 | 1.25 | 45 | 98 | 9,832 | 1.7 | 49.0 | | | Notes:

1. The Altar mineral resource was updated during 2024. 2. All mineral resources are contained in pit geometries. 3. Mineral resources for Altar are based on metal prices of $3.75/lb copper, $1,800/oz gold, $23.00/oz silver. 4. There are no mineral reserves at Altar at this time. 5. Cut-off grades are based on calculations of net smelter return (NSR) assuming the processing by flotation to produce a copper concentrate and smelting of that concentrate. 6. The Altar NSR is defined as:

Copper Contribution :

1. Float recoverable copper grade x 22.0462x(3.75-TCRC) less 1% smelter deduct Floatation recoverable copper grade = (copper grade – 0.01) *0.92

Gold Contribution :

1. (Gold grade in ppm x 0.55 /31.1035) x (1800-4.00) less 1 gram smelter deduct

Silver Contribution : 1. (Silver grade in ppm x 0.50/31.1035) x (23.00 -0.30) less 30 grams smelter deduct

1. Arsenic grades vary by block in the model and smelter terms, including arsenic penalties, vary by block. Average smelter terms, including arsenic penalties for the 2024 Altar Mineral Resource, is approximately $0.71/lb copper. 2. The equivalent copper cutoff grade of 0.24% CuEq was calculated based on the economics discussed in these footnotes and differs from the calculation of CuEq discussed elsewhere in this press release. The equivalent copper cut-off grade calculation is approximate due to the complexities of arsenic penalty calculations by block. 3. Tables may not balance exactly due to rounding. 4. The Qualified Persons for the mineral resources are John Marek RM-SME, and Jacob Richey PE, of Independent Mining Consultants, Inc. | | | | | | | | | | | | | | | | | | | | | | |

Mining

The proposed mining method is divided into open-pit mining for the near-surface part of the deposit and underground caving for the deeper parts. The open pit will use well-known truck and shovel operations with 12.5-m bench intervals. Haul trucks will be used for hauling mineralized material to the crushing plant and long-term stockpile facilities. Waste rock will be hauled to the closest waste rock storage facility. Underground operations will handle material in bulk using well established block caving methods. Open-pit mining will occur during the first 9 years of operation (in the Altar Central area), while underground development is underway. The mining profile for the project can be seen in Figure 3.

Open pit mining operations will use a smaller-scale equipment fleet that includes 8 m 3 hydraulic excavators and 100t capacity SANY haul trucks to allow for narrower bench phases and haul roads, steeper pit slopes, which will facilitate getting into the better-grade, highest-margin mineralization sooner. Underground block cave mining will occur in three areas: Altar East, Altar United, and Altar Central (beneath the open pit). Each underground cave is divided into two lifts, an upper and lower, which will be sequenced as follows: Altar East Upper, Altar United Upper, Altar Central Upper, Altar East Lower, Altar United Lower and Altar Central Lower. Underground access to the block caving mining areas will be through a portal and conveyor drift from the south of the proposed pit (twin declines). To develop the first block cave lift at Altar East, two 3000 m declines are required plus associated development beneath the cave lift.

Figure 3. Mining profile for the LOM

Processing

Extensive metallurgical test work has demonstrated that the contained copper and gold can be effectively recovered in a traditional flotation concentrator that would produce a single gold-bearing copper concentrate using industry-accepted technologies. The flowsheet includes primary crushing followed by grinding in a SAG (semi-autogenous grinding) mill/ball mill grinding circuit, rougher flotation, regrinding of the rougher concentrate and three stages of cleaner flotation. The concentrator would be constructed with a capacity to process 60,000 tpd and operated on a 365 day/year, 24 hour/day schedule. A simplified process flowsheet can be seen in Figure 4. LOM average recoveries for Cu, Au and Ag are 87.76%, 57% and 50% respectively. The grade of the concentrate produced is 26% for the LOM. Arsenic in the concentrate is expected to range from 0.5% to 2.2%. Aldebaran hired the CRU Group, a global leader in commodity research and market analysis, to complete a study analyzing the placement of arsenic-bearing concentrates into the marketplace, which showed that blending capacity for arsenic-bearing copper concentrates worldwide has increased materially in recent years, and penalties paid for arsenic-bearing concentrates have decreased substantially. The PEA utilizes CRU’s view on arsenic penalties.

Figure 4. Processing Circuit

Capital and Operating Costs

The capital cost estimate prepared for the PEA includes an installation cost associated with the site infrastructure, open pit mine and concentrator plant, a growth capital associated with the installation of the block caving underground mining operation, and the sustaining capital associated with the production plan. The LOM summary of capital is presented in Table 3, while the capital profile for the LOM is presented in Figure 5.

Figure 5. Capital Profile for the LOM

Operating costs were estimated for the open pit mining operation, block caving mining operation, the concentrator processing operation, and G&A. A summary of the estimated operating costs is presented in Table 4. The buildup of LOM C1 cash costs and AISC can be found in Tables 5 and 6, while operating costs by year can be found in Figure 6.

| Table 5. Altar C1 Cash Costs | | | | | | Item | Unit | M USD | USD/ lb Cu Payable | | | Open Pit Mining Cost | M USD | 1,208 | | 0.13 | | Block Cave Mining Cost | M USD | 6,523 | | 0.72 | | Processing Cost | M USD | 6,866 | | 0.76 | | G&A Cost | M USD | 1,388 | | 0.15 | | As Penalty | M USD | 288 | | 0.03 | | Treatment Charges (TC) | M USD | 1,150 | | 0.13 | | Cu Refining Charges (RC) | M USD | 634 | | 0.07 | | Freight Charges (FC) | M USD | 2,257 | | 0.25 | | Less: Au By-Product Credits | M USD | -1,798 | | -0.20 | | Less: Ag By-Product Credits | M USD | -221 | | -0.02 | | C1 Cost | $US/lb Payable Cu | 18,296 | | 2.02 | | | | | | |

| Table 6. Altar AISC | | | | | | Item | Unit | M USD | USD/ lb Cu Payable | | | Open Pit Mining Cost | M USD | 1,208 | | 0.13 | | Block Cave Mining Cost | M USD | 6,523 | | 0.72 | | Processing Cost | M USD | 6,866 | | 0.76 | | G&A Cost | M USD | 1,388 | | 0.15 | | As Penalty | M USD | 288 | | 0.03 | | Treatment Charges (TC) | M USD | 1,150 | | 0.13 | | Cu Refining Charges (RC) | M USD | 634 | | 0.07 | | Freight Charges (FC) | M USD | 2,257 | | 0.25 | | Less: Au By-Product Credits | M USD | -1,798 | | -0.20 | | Less: Ag By-Product Credits | M USD | -221 | | -0.02 | | San Juan Mine Mouth Tax | M USD | 972 | | 0.11 | | Total Royalties | M USD | 393 | | 0.04 | | Total Sustaining Capex | M USD | 3,830 | | 0.42 | | AISC | $US/lb Payable Cu | 23,492 | | 2.59 | | | | | | |

Figure 6. Operating Cost by Year

Infrastructure

The Altar project includes on-site infrastructure such as earthworks development, crushing and process plant facilities as well as ancillary buildings such as camp, warehouses and workshops, on-site roads, water management systems, and site electrical power facilities.

Off-site infrastructure includes a site access road, plant roads, water supply, power supply (power transmission line), two waste rock storage areas, the tailings storage facility, and surface water management structures.

Water use for the project assumes use of surface runoff water, pit dewatering wells, water supply wells within 25 km from the concentrator, with additional water supplied from surface sources.

Nuton, a Rio Tinto venture, Scenario

On November 7, 2024, Aldebaran announced that it had entered an agreement with Nuton Holdings ltd. (“Nuton”), whereby Aldebaran would grant Nuton the option to acquire a 20% stake in the Altar project (see Company press release dated November 7, 2024). As part of that agreement, Aldebaran agreed to include a case in the PEA (“Nuton Case”) utilizing the Nuton ® Technology, a suite of proprietary sulphide leaching technologies, as a potential alternative to the base case concentrator scenario reported above (“Base Case”). Nuton ® Technology provides the potential to leach both primary and secondary sulphides, providing an alternative processing option for the Altar project. In addition, the Nuton Case provides significant other benefits, such as eliminating the need for a tailings dam, providing a smaller environmental footprint, lower overall energy consumption and lower water consumption than conventional sulphide mineralization treatment processes. Moreover, producing copper cathode on site would eliminate downstream treatment and refining costs, deleterious elements’ penalties, simplify logistics and would provide a finished product at site saleable to the market.