(MENAFN- Newsfile Corp) Val-d'Or, Quebec--(Newsfile Corp. - October 16, 2025) - Bonterra Resources Inc. (TSXV: BTR) (OTCQX: BONXF) (FSE: 9BR2) ( " Bonterra " or the " Company " ) is pleased to announce the discovery of the extension of the mineralized Hewfran Zone at its 100%-owned Desmaraisville South Project (the " Project "), located immediately adjacent to historical underground workings at the Bachelor Mine.

The Hewfran Zone lies within the active Bachelor mining lease and less than 500 meters (" m ") from the Bachelor Mill Complex, offering a strategic opportunity to advance Bonterra's plan to restart mining operations using existing permitted infrastructure.

Marc-André Pelletier, President and CEO commented: "The Hewfran Zone extension confirms the strong potential that remains immediately adjacent to the previously mined Bachelor Mine workings. Located within the existing mining lease and only a short distance from the mill and underground development, Hewfran presents a compelling opportunity to support a restart scenario. Importantly, the mineralization style and host rocks are consistent with those at Bachelor Mine. With roughly half of the 2025 drill program completed, we are now focusing on Hewfran and other high-priority targets identified through VRIFY's DORA platform, as the Bachelor Mine and Desmaraisville property continue to demonstrate significant untapped potential."

Hewfran Zone Highlights

Five shallow holes were completed to evaluate the up-dip and near-surface extensions of the Hewfran Zone Vein B. Drill holes BRDS-25-076, 077, and 092 intersected zones of intense silicification and hematite alteration with disseminated pyrite, confirming that the mineralized structures remain continuous toward surface. Bonterra plans to follow up on these results as part of its ongoing effort to restart operations at the Bachelor Mine. Drill highlights from the Hewfran Zone extension are as follows:

• 2.78 g/t Au over 4.7 m, including 14.2 g/t Au over 0.7 m in hole BRDS-25-076

• 2.54 g/t Au over 8.0 m, including 6.19 g/t Au over 1.2 m in hole BRDS-25-077

• 1.32 g/t Au over 17.0 m, including 3.88 g/t Au over 4.0 m in hole BRDS-25-092

The Hewfran Zone consists of two mineralized lenses (A and B) extending from surface down to approximately 200 m below surface, positioned immediately alongside historical stopes, and underground development at the former Bachelor Mine. The mineralization style and host rock characteristics are consistent with those observed at Bachelor, comprising steeply dipping quartz-carbonate veining, silica flooding, hematite-altered stockwork, and pyrite.

Importantly, the Hewfran Zone lies within 500 m of the Bachelor Mill and surface infrastructure highlighting a low-cost, near-mine growth opportunity with direct access to existing shaft, declines, and mine services (see Figures 1 and 2 and Tables 1 and 2).

Figure 1: Desmaraisville South Project - Longitudinal View showing Hewfran A & B Veins and the Bachelor Mine Workings

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Figure 2: Desmaraisville South Project - Hewfran Plan View - B Vein New Assay Results

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2025 Drilling Update

Diamond drilling at Desmaraisville South began in early July 2025, with one drill rig currently active on site. To date, 22 diamond drill holes totaling 5,658 m have been completed. A total of 32,911 NQ core samples, along with 514 associated QA/QC samples, have been submitted to accredited laboratories, with 1,148 assay results pending. Fieldwork, including detailed mapping and sampling, continues across the property.

The ongoing 10,000-12,000 m drill campaign, scheduled for completion by year-end, was initially designed to follow up on previous drilling at the Hewfran, Mistik 13, and Le Sueur targets, as well as to test additional targets generated using VRIFY's AI-assisted discovery platform, DORA. Following the encouraging intercepts at Hewfran, the remainder of the program will now prioritize step-out and delineation drilling in that area, and other high-priority targets near the Bachelor Mill Complex.

All targets are located in close proximity to the Bachelor Mill Complex, where historical production exceeded 350,000 ounces of gold from two million tonnes of ore at an average grade of 5.0 g/t Au.

Mistik 13 and Le Sueur

At Mistik 13, new drilling tested the western and northern extensions of the gold intercept reported in hole BRDS-23-013 (0.80 g/t Au over 11.7 m, including 2.84 g/t Au over 1.4 m; see press release dated February 5, 2024). Drill holes BRDS-25-081 and BRDS-25-082 intersected a mineralized shear zone characterized by abundant silica alteration with lesser sericite and carbonate and disseminated pyrite. The gold mineralization appears to be associated with a northwest-southeast trending geological structure adjacent to a felsic dike (see Figure 3).

At Le Sueur, visible gold (" VG ") was intercepted in hole BDRS-25-085 at proximity of an historical showing discovered in 1990 by SEREM (10.97 g/t Au over 1.5 m). Drill highlights from Mistik 13 and Le Sueur are as follows:

• 0.24 g/t Au over 21.5 m in hole BRDS-25-081(Mistik 13)

• 3.05 g/t Au over 4.61 m, including 23.3 g/t Au over 0.5 m in hole BRDS-25-082 (Mistik 13)

• 1.17 g/t Au over 0.45 m with visible gold in hole BRDS-25-085 (Le Sueur)

Figure 3: Desmaraisville South Project - Mistik 13 and Le Sueur Plan View New Assay Results

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2025 Field Work Campaign

The 2025 mapping and sampling program at Desmaraisville South commenced on August 11th with a two-person field crew. This work builds on the property-wide mapping and sampling program initiated in 2024. To date, a total of 66 grab samples and 46 lithogeochemistry samples have been collected and submitted for analysis at AGAT Laboratories in Val-d'Or, QC and Thunder Bay, ON.

Table 1: Drill Hole Locations - Desmaraisville South project, Québec

Hole ID	Easting	Northing	Elevation (m)	Azimuth	Dip	Length (m)
BRDS-25-76	416515	5483404	307.3	30	-50	330
BRDS-25-77	416689	548331.8	318.0	19	-51	153
BRDS-25-81	418307	5485899	311.0	189	-50	282
BRDS-25-82	418217	5485944	302.0	189	-50	303
BRDS-25-092	416515	5483404	307.0	65	-55	201
BRDS-25-085	417454	5486573	314.0	205	-50	201
UTM Coordinates, System: NAD83 Zone 18

Table 2: Significant Mineralized Intersections from Drilling on the Desmaraisville South project

Hole ID	Zones	From (m)	To (m)	Length (m)	Grades (g/t Au)	Metal Factor (Length x Grade)
BRDS-25-76	Hewfran B	82.0	86.7	4.7	2.78	13.1
	Including	85.3	86.0	0.7	14.20	9.9
BRDS-25-77	Hewfran B	114.3	122.3	8.0	2.54	20.3
	Including	115.8	117.0	1.2	6.19	7.4
BRDS-25-81	Mistik 13	101.0	122.5	21.5	0.24	5.1
BRDS-25-82	Misitk 13	129.0	133.61	4.61	3.05	14.1
	Including	130.0	130.5	0.5	23.3	11.7
BRDS-25-092	Hewfran B	146.0	163.0	17.0	1.32	22.5
	including	157.0	161.0	4.0	3.88	15.5
BRDS-25-085*	Le Sueur	167,5	168,0	0.5	1.17	0.6
1) Reported intervals represent drilled core lengths; true widths are not yet known. 2) Gold results obtained above<0.5 g/t Au with a Metal Factor above 5 except for Le Sueur drill hole where VG was intercepted. 3) * Visible Gold (VG)

Quality Control and Reporting Protocols

The Desmaraisville South Project's drill core gold analyses were performed at the MSALABS and the AGAT Laboratories located in Val-d'Or, Québec. These external laboratories employ a rigorous QA-QC analysis program that meets industry standards. At the AGAT laboratory, the analyses are carried out by fire assay (A.A.) with atomic absorption finish and with gravimetric finish for assay above 10 g/t Au. Blanks, duplicates, and certified reference standards are inserted into the sample stream to monitor the Laboratory's performance. Other core samples gold analysis was performed at MSALABS of Val d'Or, Québec. The samples were crushed to a particle size of 70% passing through a two-millimeter sieve, and then a 500-gram portion was taken for gold analysis by gamma ray (PhotonAssayTM). As per MSALABS' internal procedure, blank samples, and certified reference materials are systematically inserted into the analysis sequence. MSALABS operates several laboratories worldwide and holds ISO-17025 accreditation for numerous metal determination methods, including the photon assay method.

The Company's QA-QC program requires that at least 5 to 10% of the samples be analyzed by an independent laboratory. These verification samples are sent to ALS Minerals laboratory facility located in Val-d'Or, Québec. The verifications show a high degree of correlation with the laboratory's results.

Qualified Person

M. Donald Trudel, P.Geo. (OGQ # 813), Director Geology for the Company, oversees all exploration activities on the Desmaraisville Property and has compiled and approved the information contained in this press release. Mr. Trudel is a qualified person as defined by National Instrument 43-101 on standards of disclosure for mineral projects.

About Bonterra Resources Inc.

Bonterra is a Canadian gold exploration company with a portfolio of advanced exploration assets anchored by a central milling facility in Quebec, Canada. The Company's assets include the Gladiator, Barry, Moroy, and Bachelor gold deposits, which collectively hold 1.24 million ounces in Measured and Indicated categories and 1.78 million ounces in the Inferred category.

In November 2023, the Company entered into an earn-in and joint venture agreement with Osisko Mining Inc. for the Urban-Barry properties (the " JV Agreement "), which include the Gladiator and Barry deposits. In October 2024, Gold Fields Ltd, through a wholly owned Canadian subsidiary, completed the acquisition of Osisko Mining for C$2.16 billion. Gold Fields is now the counterparty to the JV Agreement and can continue to earn a 70% interest in the joint venture by incurring C$30 million in work expenditures until November 2026 (including expenditures incurred by Osisko Mining prior to October 2024). This strategic transaction highlights Bonterra's dedication to advancing its exploration assets, marking a significant step towards development.

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