ATERRA Metals Unveils Strong Phase I Drill Outcomes at Chile's Totora Copper-Gold Project

Frontera Deposit Demonstrates High-Grade Mineralization from Surface

The Frontera Cu/Au Deposit stands as the focal point of ATERRA's Totora project, with Phase I drilling confirming a core zone of elevated copper and gold grades. A single diamond drill hole, AFROD01, intersected 284 metres grading 0.64% copper equivalent from surface. Within this, a higher-grade segment of 180 metres averaged 0.71% CuEq, including a 70-metre interval at 0.82% CuEq. These findings indicate continuous mineralization from surface downward, a key factor for development potential.

The deposit contains a historical resource estimate from March 2014 by Hot Chili Limited, reporting 16 million tonnes indicated at 0.56% copper equivalent and 34 million tonnes inferred at 0.54% copper equivalent, prepared under the JORC Code (2012 Edition). ATERRA's recent drilling intersects core material with grades surpassing historical averages, suggesting potential for resource growth. The Frontera Deposit "remains open to depth," indicating further mineralization beyond current estimates.

Totora Porphyry Confirms Continuous Copper-Gold Mineralization

The Totora Cu/Au Porphyry target within ATERRA's concessions has been validated as a continuous mineralized system across multiple drill sites. Hole ATOD01 intersected 194 metres grading 0.41% copper equivalent starting at 254 metres downhole. Mineralization "continues to surface and remains open to depth," implying the system extends vertically beyond tested depths.

Six additional exploration holes (ATOR01, ATOR03, ATOR03A, ATOR04, ATOR04D, ATOR05) tested lateral extensions of the main porphyry. Results revealed a mineralized southwest extension in holes ATOR03A, ATOR04/4D, and ATOR05. Hole ATOD08, filling a gap between the main porphyry and southwest extension, returned 82 metres grading 0.35% copper equivalent at a 0.2% cutoff, indicating a continuous copper-gold trend. One reverse circulation hole (ATOR01) was lost at 208 metres; hole ATOR02 on the eastern margin showed no significant mineralization.

Algarrobilla and Clinton Porphyries Exhibit Early Exploration Potential

Beyond Frontera and Totora, ATERRA tested the Algarrobilla Cu/Au Porphyry about 1 kilometre south of Totora. Two holes were drilled: ATOR06 yielded two intervals of above-cutoff copper equivalent mineralization, while ATOR07 showed no significant results. Planned geophysical surveys aim to further delineate mineralization along the Algarrobilla trend.

The Clinton Cu/Au Porphyry was not drilled in Phase I due to availability of substantial historical diamond drill core for review. This strategy allows ATERRA to utilize existing data before allocating drilling resources. Clinton will be included in the upcoming 43-101 compliant resource estimate alongside Frontera and Totora.

Strategic Location Offers Infrastructure and Regulatory Benefits

ATERRA's Totora project lies in Chile's Dos Amigo Mining District, 15 kilometres south of Tintina Mines' Domekyo Sulfurous project. CEO Carl Hansen highlighted the district's "excellent regional infrastructure, low elevations, and proximity to water," which reduce operational costs and complexity compared to higher-altitude or remote sites. The low elevation also lowers energy demands and simplifies logistics for potential development.

The Dos Amigo District has attracted major investments, including Sumitomo and the Gignac family's strategic stake in Tintina Mines, and Hot Chili's La Verde copper-gold discovery. This cluster of advanced projects indicates supportive geology, permitting, and market conditions, potentially lowering regulatory and geopolitical risks for ATERRA investors.

Phase II Drilling Aims to Expand Resources and Enhance Confidence

ATERRA's Phase II drilling campaign targets increased resource confidence and expansion of known mineralization. At Frontera, efforts will focus on enlarging the resource base and extending the higher-grade core zone. Infill drilling aims to upgrade inferred resources to measured and indicated categories, essential for feasibility studies and financing. At Totora, drilling will seek to expand mineralization boundaries and infill areas with wide drill spacing.

An independent consulting firm will prepare a 43-101 compliant mineral resource estimate integrating Frontera, Totora, and Clinton results. This comprehensive assessment will underpin future technical and economic evaluations. No timeline has been provided for the resource estimate completion or Phase II drilling start.

Phase I Program Totaled 2,745.5 Metres of Drilling

The Phase I drill program comprised 2,745.5 metres across multiple holes targeting Frontera, Totora, and Algarrobilla porphyries, using reverse circulation (RC) and diamond drilling. Phase 1a holes employed RC with a 5½-inch bit; Phase 1b holes used HQ diamond bits. RC cuttings were collected and split onsite under geologist supervision; diamond core was logged, cut, and prepared for shipment.

Samples were sent to AGS Cotecna laboratory in Coquimbo for preparation and analysis. Gold was assayed by fire assay with a 30-gram charge and atomic absorption finish (detection limit 0.005–10 g/t). Copper was analyzed by four-acid digestion with atomic absorption (detection limit 0.001–5%). Silver and molybdenum were secondary elements. QA/QC showed "no data quality issues." Copper equivalent grades assumed 85% metallurgical recovery for copper and gold, noting actual recoveries may vary.

Copper Equivalent Grades Calculated Using Fixed Metal Price Assumptions

ATERRA calculated copper equivalent (CuEq) grades based on commodity prices of US$4.00 per pound copper and US$3,500 per ounce gold (US$112.53 per gram). The formula used was: CuEq% = (((Au grade × 0.85 × 112.53) / 4.00 / 2,204.6) × 100) + (Cu grade × 0.85), incorporating 85% metallurgical recovery for both metals. These fixed prices and recovery assumptions mean CuEq grades do not reflect actual market price fluctuations or processing recoveries.

National Instrument 43-101 requires disclosure of assumed recoveries when no metallurgical testwork exists, which ATERRA has provided. Investors should recognize that economic value depends on actual recovery rates and metal prices at potential development or sale, which may differ materially from assumptions.

Management Highlights Project Potential and Regional Momentum

CEO Carl Hansen described Phase I results as "impressive," emphasizing confirmed mineralization at Frontera and Totora. He stated the deposits "have the potential to host significant mineral resources" and underscored the strategic advantage of the project's location within a growing mining district. Hansen cited recent investments by Sumitomo and the Gignac family in Tintina Mines as evidence of confidence in the regional geology and permitting.

Hansen confirmed ATERRA will "engage an independent consulting firm to prepare a 43-101 compliant mineral resource, comprising the Frontera, Totora, and Clinton porphyries," aiming to add the Totora Copper Gold Project to the portfolio of notable developments in the Dos Amigo Mining District.

Research Capital Advisory Agreement and Share Issuances

On March 26, 2026, ATERRA retained Research Capital Corporation (RCC) as financial advisor for three months. In return, ATERRA agreed to issue RCC 5,750,000 common shares in three monthly tranches. The final tranche of 1,916,667 shares was issued on June 28, 2026, at a deemed price of $0.0314 per share, totaling $60,183.34. Shares are subject to a four-month hold period until September 28, 2026, per Canadian Securities Exchange rules.

This advisory engagement and share issuance is common in junior exploration, supporting capital markets and investor relations efforts. The hold period restricts immediate resale, potentially reducing short-term selling pressure on ATERRA's stock.

Qualified Person Disclosure and Historical Resource Context

Francisco Bravo, ATERRA's Chief Geologist based in Santiago, Chile, serves as the "Qualified Person" under National Instrument 43-101. Bravo is a Public Registered Person for Reserves and Resources (No. 515) in Chile and registered with the Colegio de Geólogos de Chile (No. 725). He is "not independent" per NI 43-101 due to employment with ATERRA and has reviewed and approved the technical content.

ATERRA has not independently verified the historical resource estimate for Frontera, prepared by Hot Chili Limited in March 2014 under the JORC Code. The company cautions readers against relying solely on historical data but considers it valuable for guiding future exploration and regards it as reliable for planning purposes.