ATERRA Updates Totora Inferred Mineral Resource and Files NI 43-101 Technical Report

ATERRA’s updated resource shrinks but drill program and funding are in place for next steps.

What the company is saying

ATERRA Metals Inc. is presenting a revised Inferred Mineral Resource estimate for its Totora Copper-Gold Project in Chile, emphasizing technical rigor and transparency. The company highlights a total resource of 150.1 million tonnes at 0.305% copper and 0.159 g/t gold, or 0.517% copper equivalent, with contained metals of 1,009 million pounds copper and 768.7 thousand ounces gold. Management, led by CEO Carl Hansen, openly acknowledges a 6.1% reduction in tonnage and lower contained metals compared to the September 2026 estimate, attributing this to the exclusion of isolated blocks at depth after refining extraction constraints. The tone is factual, with no attempt to minimize the downgrade, and the company stresses that average grades have slightly improved. ATERRA communicates that it has secured $8.355 million in financing and will imminently launch a 13,000-metre drill program to test extensions and infill across all deposits, as well as conduct metallurgical sampling. The company also notes a signed contract for a magnetotelluric survey to identify further targets. The resource remains entirely in the Inferred category, and the company is explicit about the technical and economic uncertainties that remain.

What the data suggests

The updated resource estimate now stands at 150.1 million tonnes grading 0.305% copper and 0.159 g/t gold, or 0.517% copper equivalent at a 0.20% copper cut-off. Contained metals are 1,009 million pounds copper and 768.7 thousand ounces gold, equivalent to 1,710.5 million pounds copper equivalent. Compared to the September 24, 2026 estimate, total tonnes are down 6.1%, contained copper is down 5.5%, and contained gold is down 3.0%, with the majority of the loss from the Totora-Algarrobilla deposit. Average copper and gold grades have increased slightly, but the overall resource base is smaller. The resource is classified entirely as Inferred, meaning it is subject to a high degree of uncertainty and cannot be considered economically viable at this stage. The company has closed $8.355 million in financing and is set to begin a 13,000-metre drill program and a magnetotelluric survey within weeks. Technical parameters are clearly disclosed: US$6.00/lb copper and US$3,650/oz gold price assumptions, mining cost of US$1.20/t plus US$0.23/t-km transport, processing cost of US$11.30/t, G&A of US$0.30/lb, selling costs of US$0.418/lb copper and US$5/oz gold, and a 10% discount rate. No metallurgical recoveries have been confirmed by test work. The company’s disclosures are comprehensive, with responsible qualified persons named and verification procedures described.

Analysis

The announcement is a technical update on the Totora Copper-Gold Project's Inferred Mineral Resource, with all key figures and changes from the prior estimate clearly disclosed and reconciled. The tone is positive, but the language is proportionate to the facts: the company transparently reports a decrease in resource tonnage and contained metals, and does not attempt to overstate the significance of the update. Forward-looking statements are limited to the planned drill program and survey, both of which are funded and scheduled to begin imminently, making the execution distance near-term. There is no evidence of exaggerated claims about future production or economic outcomes, and the risks and uncertainties associated with the Inferred Resource classification are explicitly acknowledged. The $8.355 million financing is sized for exploration, not large-scale development, so capital intensity is low at this stage. Overall, the narrative closely matches the disclosed evidence, with no material inflation or hype.

Risk flags

• ●The entire resource remains classified as Inferred, which means there is a high degree of geological and economic uncertainty. Inferred resources cannot be assumed to be economically viable, and there is no assurance that further work will convert them to higher-confidence categories.
• ●The resource revision resulted in a 6.1% reduction in tonnage and lower contained metals, primarily due to the exclusion of isolated blocks at depth. This demonstrates the sensitivity of the resource to conceptual extraction models and highlights the risk that further technical refinements or drilling could further reduce the resource base.
• ●The company’s option agreements require future payments and exploration commitments to maintain or increase its property interests. Failure to meet these obligations could result in the loss of some or all project rights, directly impacting project continuity.
• ●No metallurgical testing has been completed on the current resource, so recovery assumptions are unproven. Actual recoveries may differ materially from those assumed, affecting the economic potential of the project.
• ●The project is exposed to external risks including metal price volatility, operating cost changes, permitting, water and infrastructure availability, environmental requirements, tenure, community relations, and potential changes in Chilean law or regulation. Any of these factors could materially impact project development.

Bottom line

ATERRA Metals’ updated Inferred Mineral Resource for the Totora Copper-Gold Project is smaller than previously reported, with a 6.1% drop in tonnage and lower contained copper and gold, though average grades have improved slightly. The company is transparent about the downgrade and has secured $8.355 million in financing to fund a 13,000-metre drill program and geophysical survey, both set to begin imminently. All resource figures remain in the Inferred category, so the project’s economic viability is highly uncertain and dependent on future drilling, metallurgical testing, and technical studies. Key risks include the untested nature of recoveries, the need to meet ongoing option agreement obligations, and exposure to external factors such as permitting and regulatory changes in Chile. Investors should focus on the results of the upcoming drill program and any progress in upgrading the resource category or confirming metallurgical recoveries. The most important takeaway is that while the resource base has shrunk, the company is well-funded for near-term exploration that could improve project confidence if results are positive.

Announcement summary

(CSE:ATC, OTCQB:CSSCF) ATERRA Metals Inc. announced an updated Inferred Mineral Resource estimate for its Totora Copper-Gold Project in Region III, Chile, with an effective date of October 27, 2026. The updated estimate, prepared by SRK Consulting (Chile) SpA, supersedes the September 24, 2026 estimate and reflects refinements to the conceptual constraints for reasonable prospects for eventual economic extraction (RPEEE). The updated Inferred Mineral Resource totals 150.1 million tonnes grading 0.305% copper and 0.159 g/t gold, or 0.517% copper equivalent (CuEq), at a base-case cut-off grade of 0.20% Cu. Contained metals are 1,009 million pounds of copper and 768.7 thousand troy ounces of gold, equivalent to 1,710.5 million pounds CuEq. The resource comprises the Frontera, Clinton, and Totora-Algarrobilla deposits. The Frontera deposit contains 79.9 Mt at 0.337% Cu and 0.191 g/t Au, Totora-Algarrobilla contains 54.3 Mt at 0.280% Cu and 0.095 g/t Au, and Clinton contains 15.8 Mt at 0.232% Cu and 0.221 g/t Au. The updated estimate reports 6.1% fewer tonnes, 5.5% lower contained copper, and 3.0% lower contained gold compared to the September 24 estimate, with slightly higher average copper and gold grades. The majority of the tonnage loss was from the Totora-Algarrobilla deposit, where 8 million fewer tonnes were reported. The updated conceptual open-pit shells use a copper price of US$6.00/lb and a gold price of US$3,650/oz. Mining costs are US$1.20/t plus US$0.23/t-km transport, processing costs are US$11.30/t processed, G&A is US$0.30/lb sold, selling costs are US$0.418/lb copper and US$5/oz gold, and a 10% discount rate is applied. Underground mining cost is US$8.50/t. The company has closed a $8.355 million financing and intends to commence a 13,000-metre drill program in November 2026, focusing on extensions of the Frontera deposit and Totora mineralized system, as well as infill drilling and metallurgical sampling. A contract has been signed for a magnetotelluric survey to identify potential extensions and new targets. The resource estimate remains classified entirely as Inferred and is subject to confirmation through future test work and various development risks. The independent Qualified Person for the Mineral Resource is Joled Nur, RM CMC, Registration No. 181, of SRK. Sophia Bascuñán, RM CMC, Registration No. 518, of SRK is responsible for geological modelling and data verification. Francisco Bravo, Chief Geologist of ATERRA Metals and a resident of Santiago, Chile, is a qualified person for the remaining technical information. Data verification included site visits, collar verification, and review of core and QA/QC procedures. Drilling included both diamond and reverse-circulation methods, with samples analyzed at AGS Cotecna laboratory in Coquimbo. The Totora Project is located in Chile's Dos Amigos Mining District with access to highway and high-voltage power infrastructure.

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