Toronto, Ontario--(Newsfile Corp. - April 21, 2026) - ATERRA Metals Inc. (CSE: ATC) (OTCQB: CSSCF) ("ATERRA") is pleased to report that the Phase 1 reverse circulation ("RC") drilling program on its Totora Cu/Au Project has been completed with 1,575 metres ("m") drilled (see Figures 1 and 2). A few of the RC holes were stopped early when water inflow began to impact sample collection, however, these holes will be extended by diamond drilling to the target depths (see Table 1). A diamond drill rig is scheduled to be mobilized within a week.

At the primary Totora Cu/Au porphyry target, RC drilling confirmed the presence of an altered quartz diorite with locally disseminated pyrite and chalcopyrite associated with quartz veining and moderate to strong potassic (sericite, biotite, ± magnetite) alteration. The mineralogy and alteration are similar to that observed in the historical drill core from the Totora porphyry. See the ATERRA press release dated February 3, 2026 for further information on the historical drilling results from the Totora Project.

Two kilometres south of the Totora porphyry, 2 shallow drill holes tested the continuity of the Algarrobilla porphyry mineralization between 100-metre spaced historical drill holes. Sulphide mineralization (primarily pyrite and chalcopyrite) was observed in both drill holes. The 2 RC holes did not reach the planned depths and a decision as to whether to extend both drill holes will be made upon receipt of assays.

Commenting on the drill program, Carl Hansen, CEO of ATERRA, stated: "Other than encountering more water than anticipated, the RC drill program progressed quickly and safely. While the amount of RC drilling was reduced due to the water, this reduction will be offset by an increased amount of diamond drilling. All samples from the RC program have been shipped to the lab for assaying. It is anticipated that we'll start to receive assay results within a couple of weeks and results will be released shortly thereafter."

Table 1 - Phase I Drilling Details (to-date), Totora Project

Figure 1 - Totora Cu/Au Porphyry - Phase 1 Drill PlanTo view an enhanced version of this graphic, please visit:
https://images.newsfilecorp.com/files/7721/293537_972c5052945199a0_001full.jpg

Figure 2 - Algarrobilla Cu/Au Porphyry - Phase 1 Drill Plan

To view an enhanced version of this graphic, please visit:
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NI 43-101 Disclosure

Qualified Person: As defined by National Instrument 43-101 ("NI 43-101") of the Canadian Securities Administrators, the "Qualified Person" for ATERRA Metals Inc. is Francisco Bravo, a resident of Santiago, Chile. As ATERRA's Chief Geologist, Mr. Bravo is considered "not independent" as the term is defined by NI 43-101. Mr. Bravo, a Public Registered Person for Reserves and Resources N° 515, in Chile, and registered in the Colegio de Geólogos de Chile under N° 725, has reviewed and approved the technical information contained in this press release.

Copper Equivalent Estimation: Copper equivalent ("CuEq") grades were estimated using a copper price of US$4.00 per pound and a gold price of US$3,500 per ounce (US$112.53 per gram). CuEq grades are estimated using the following formula: CuEq% = ((Au grade * 0.85 * 112.53) / 4.00 / 2,204.6)) * 100 + (Cu grade * 0.85).

Regulatory requirements for disclosure of CuEq grade estimates require an estimation of metallurgical recoveries in the situation where no metallurgical testwork has been completed. ATERRA estimates copper recoveries of 85% and gold recoveries of 85%. It is important to note the actual recoveries will likely vary from those used in the estimation of the CuEq grades.

Historical Results: ATERRA has not undertaken any independent investigation of any historical results from the Totora Project nor has it verified the underlying technical basis for the historical resources and drilling results. The reader is cautioned against relying on the accuracy of the historical results presented; however, ATERRA considers all historical results relevant as those results will be used as a guide to plan future exploration programs: ATERRA considers the data to be reliable for these purposes.

About ATERRA Metals Inc.

ATERRA is a mineral exploration company focused on exploration opportunities in Chile. ATERRA's team of successful exploration professionals are dedicated to the discovery of mineral deposits that can be progressed into economically viable development projects creating value for all stakeholders.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This news release contains forward-looking statements, including predictions, projections and forecasts. Forward-looking statements include, but are not limited to: plans for the evaluation of exploration properties; the success of evaluation plans; the success of exploration activities; mine development prospects; and, potential for future metals production. Often, but not always, forward-looking statements can be identified by the use of words such as "plans", "planning", "expects" or "does not expect", "focus is to", "continues", "scheduled", "estimates", "forecasts", "objectives", "intends", "potential", "anticipates", "does not anticipate", or describes a "goal", or variation of such words and phrases or state that certain actions, events or results "may", "could", "would", "might", or "will" be taken, occur or be achieved.

Forward-looking statements involve known and unknown risks, future events, conditions, uncertainties and other factors which may cause the actual results, performance or achievements to be materially different from any future results, prediction, projection, forecast, performance or achievements expressed or implied by the forward-looking statements. Such factors include, among others: changes in economic parameters and assumptions; all aspects related to the timing of exploration activities and receipt of exploration results including assays; the interpretation and actual results of current exploration activities; changes in project or exploration parameters as plans continue to be refined; the results of regulatory and permitting processes; future metals prices; possible variations in grade or recovery rates; variations in the recovery rates used in the calculation of equivalent grades; failure of equipment or processes to operate as anticipated; labour disputes and other risks of the mining industry; the results of economic and technical studies; delays in obtaining governmental approvals or financing or in the completion of exploration; as well as those factors disclosed in ATERRA's publicly filed documents.

Although ATERRA has attempted to identify important factors that could cause actual actions, events or results to differ materially from those described in forward-looking statements, there may be other factors that cause actions, events or results not to be as anticipated, estimated or intended. There can be no assurance that forward-looking statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements.

Neither the Canadian Securities Exchange nor its regulation services provider has reviewed or accepts responsibility for the adequacy or accuracy of the content of this news release.

To view the source version of this press release, please visit https://www.newsfilecorp.com/release/293537

Source: ATERRA Metals Inc.