Patterson, Idaho and Toronto, Ontario--(Newsfile Corp. - September 17, 2026) - American Tungsten Corp. (TSXV: TUNG) (OTCQX: TUNGF) (FSE: RK90) ("American Tungsten" or the "Company") is pleased to announce significant results from completed drillholes on the Zero and D-Levels of the IMA Mine, Lemhi County, Idaho.

"Crossing the 30,000-foot drilling threshold marks another important step in defining the scale and continuity of the IMA Mine mineral system," said Austin Zinsser, Vice President of Exploration. "The latest results not only expand the known extent of the No. 5 through No. 7 vein array, but also confirm the historic 41R vein and identifies additional tungsten-bearing zones beyond previously mined areas. Together, these intersections continue to reinforce our view that IMA hosts a significantly larger mineralized system than previously recognized, while highlighting the considerable exploration potential that remains both adjacent to and beyond the historic mine workings."

Drill Results Highlights:

• In late August, American Tungsten surpassed 30,000 ft of completed drilling since December, 2025–producing over 5.5 miles of core.
• Drillholes AT26-36 and AT26-43 each intersected the stacked No. 5 – No. 7 vein array, building on the previously announced 900 ft of strike length, including:
  • 6.7 ft grading 0.547% WO₃ and 2.38 oz/t Ag in the No. 5 vein in hole AT26-43
  • 14.8 ft grading 0.470% WO₃ and 1.24 oz/t Ag in the No. 7 vein in hole AT26-43
  • 5.05 ft grading 0.550% WO₃ and 1.45 oz/t Ag in the No. 5 vein in hole AT26-36
• Exploratory down holes from the D-Level encountered previously unknown areas of mineralization, including 5 ft grading 0.484% WO₃ in hole AT26-45
• Vein 41R, a previously untested historic vein, was intersected from the Zero Level in multiple drillholes, including:
  • 9.4 ft grading 0.802% WO₃ and 0.59 oz/t Ag in the 41R vein in hole AT26-39
  • 3.3 ft grading 0.639% WO₃ and 0.84 oz/t Ag in the 41R vein in hole AT26-35
• Deep surface drillholes intersected multiple tungsten-bearing polymetallic veins adjacent to and within the Ima Stock, including:
  • 10.6 ft grading 0.955% WO₃ and 1.14 oz/t Ag in hole AT26-48S
  • 5.3 ft grading 0.777% WO₃ in hole AT26-48S

Drill Results

Holes AT26-43 and AT26-36 were drilled as an upward-inclined fan from drill station #3 on the D-Level, continuing to test from the footwall of the historically mined areas and expanding on the Company's July 29, 2026 announcement, which confirmed over 900 ft of strike length within the stacked tungsten-bearing No. 5 – No. 7 vein array. Both holes intersected the No. 5, No. 6, No. 7 and No. 8 veins, including 14.8 ft grading 0.470% WO₃ and 1.24 oz/t Ag in the No. 7 vein in hole AT26-43.

Figure 1: Core boxes 24 and 25 from AT26-43, annotated to show No. 7 vein intercept: 14.8 ft grading 0.470% WO₃ and 1.24 oz/t Ag. Pink flagging denotes sample breaks.

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On the Zero Level, a new polymetallic vein system was successfully intercepted in holes AT26-35 and AT26-39, with 9.4 ft grading 0.802% WO₃, including 4.4 ft grading 1.551% WO₃ and 1.05 oz/t Ag in AT26-39. Historically called the "41R Vein" and associated with the 4S stope between the Zero Level and 100-Level, the area was targeted with both a downward and inclined fan drill pattern, to test continuity along dip. Importantly, this area had not previously been tested in American Tungsten's drill program demonstrating the significant exploration upside of the system adjacent to historical mining. An adjacent hole, AT26-50, intersected 16.1 ft grading 0.548% WO₃ and 2.48 oz/t Ag before encountering a lobe of the Ima Stock, host to 20 ft grading 0.2% MoS₂. Geological modeling is ongoing to assess relationships between the Ima stock and associated quartz vein hosted mineralization in the 41R and subsidiary veins.

Surface drillhole AT26-48S was targeted below the zero level and intersected a significant tungsten bearing quartz vein estimated at 7 ft true width approximately 400 feet southwest of the main Ima underground development area and additional minor veins within the Ima stock at depth. Only partial assays have been received for AT26-40S and no significant intercepts are reported.

New drillhole results are reported in Table 1 below. Assays for additional completed drillholes are pending, and drillholes are not always numbered or logged sequentially. AT26-42 and AT26-40S have roughly half of their samples still pending, and are reported here only for their returned portions.

Table 1: Summary drillhole assay results from the Ima tungsten project

1. True width is estimated at 65-70% for AT26-36 & AT26-43 and upper intercept in AT26-48S. True width is estimated at 75-90% for AT26-35 and AT26-39. True width is estimated at 60-65% for AT26-42 and AT26-50. True width of intercepts in AT26-45, AT26-40S and lower intercepts in AT26-48S is unknown.
2. WO3 and MoS2 % values are calculated from ppm analyses based on stoichiometry factors of 1.2611 and 1.668; silver is reported in troy ounces per ton.
3. Composites are generated using cut-off grades of 0.1% WO3 or 0.5 oz/t Ag or 0.05% MoS2, and may include internal waste below cut-off grade.

Figure 2: Drillhole location map showing D level, Zero level and surface DH intercepts

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About the IMA Mine

The IMA Mine is a past-producing underground tungsten mine situated on 22 patented claims located in east-central Idaho. Between 1945 and 1957, the property produced approximately 199,449 MTUs of WO₃ and was subsequently explored for molybdenum and tungsten by various operators between 1960 and 2010. The Company recently announced a Mineral Resource Estimate for the IMA Mine comprising 316,000 tonnes of Indicated Mineral Resources grading 0.55% WO₃, containing 1,747 tonnes of WO₃, and 2,178,000 tonnes of Inferred Mineral Resources grading 0.55% WO₃, containing 11,933 tonnes of WO₃, in addition to a surface tailings resource containing 267,000 tonnes of Indicated Mineral Resources grading 0.15% WO₃ and containing 413 tonnes of WO₃. The mineral resource estimate supports the Company's strategy of advancing the IMA Mine toward potential domestic tungsten production through a phased development approach. American Tungsten is currently conducting an exploration drill program, advancing engineering and technical studies, and assessing the potential restart of underground tungsten mining operations at the IMA Mine. (National Instrument 43-101 Technical Report on the IMA Mine, Patterson, Idaho, USA, p. 29; LeBlanc, B., P.Eng. (2025), A-Z Mining Professionals, with an effective date of June 6, 2025 and revised May 27, 2026; and the Company's August 20, 2026 Mineral Resource Estimate news release.)

About American Tungsten Corp.

American Tungsten Corp. is a Canadian-based exploration and development company focused on advancing the IMA Mine Project, a high-quality, private-patented, past-producing underground tungsten mine located in Idaho, USA. The Company's strategy is centered on advancing the IMA Mine back toward commercial production through a clearly defined, phased development approach. Phase I involves the evaluation and potential processing of existing surface tailings, providing a lower-capital pathway to potential near-term production. Phase II is focused on the rehabilitation and potential restart of the historic underground mine, leveraging the site's extensive existing infrastructure and historical production profile.

With tungsten recognized as a critical metal for defense, industrial manufacturing and advanced technologies, American Tungsten is focused on re-establishing domestic tungsten production and supporting North American supply-chain security. www.americantungstencorp.com

Sampling Methodology

Underground drillholes were completed using Hagby 1000 or Sandvik 130 drill rigs with NQ sized rods. Surface drillholes were completed using a AR-175 or Longyear 44 with HQ sized rods. Drill core was transferred to American Tungsten geologists under chain of custody and stored in a secure facility. Drill core was logged for lithology, alteration, mineralization, and structure prior to sampling. Sample number tags were affixed to core boxes and core marked for sawing. Core was sawn in half, with one half submitted for analysis and the remaining half retained for reference. Samples were collected at approximate 5 foot intervals in wall rock and shorter intervals within vein mineralization, with sample lengths adjusted to geological boundaries where appropriate. Samples were submitted for assay to ALS Global in Twin Falls, Idaho.

QA/QC and Sample Analysis

American Tungsten Corp's Quality Assurance and Quality Control QA/QC program applies industry standard best practices to ensure data quality and integrity for the IMA Mine project, including maintaining chain of custody, secure sample transport and storage, adherence to data collection protocols and inclusion of certified reference, blank and duplicate quality assurance samples in laboratory submissions.

Samples were submitted to ALS Global laboratory in Twin Falls, Idaho, for preparation. Samples were crushed to 70% passing 2 mm screen, rotary splitting 250g and pulverized to 85% passing a 75 μm screen. Samples were analyzed by ALS Minerals in the Vancouver, BC, Canada. Samples were analyzed by four acid digest with ICP-MS finish. Samples exceeding 200 ppm W were analyzed by XRF with lithium borate fusion preparation. Samples exceeding 50ppm Ag were analyzed by fire assay with gravimetric finish.

Qualified Person

Technical information in this news release has been prepared in accordance with Canadian regulatory requirements set out in National Instrument 43-101 — Standards of Disclosure for Mineral Projects ("NI-43-101"). Austin Zinsser, P.G., SME-RM, Vice President, Exploration for the Company, and a Qualified Person as defined by NI-43-101, has reviewed and approved the scientific and technical information in this news release.

Social media links:

https://www.linkedin.com/company/americantungstencorp/
https://x.com/amtungsten
https://www.facebook.com/americantungstencorp/
https://www.instagram.com/americantungstencorp/
https://www.youtube.com/@americantungstencorp

Cautionary Statements

This news release contains forward-looking statements and forward-looking information (collectively, "forward-looking statements") within the meaning of applicable Canadian securities laws. Any statements that are contained in this news release that are not statements of historical fact may be deemed to be forward-looking statements. Forward-looking statements are often identified by terms such as "may", "should", "anticipate", "will", "estimates", "believes", "intends", "expects" and similar expressions which are intended to identify forward-looking statements. Forward-looking statements in this news release include, but are not limited to, statements regarding: the Company's planned exploration and drilling programs; the timing and cost of anticipated exploration activities; the prospective mineralization of the Company's properties; the potential delineation of mineral resources; and the acquisition of necessary permits and regulatory approvals. More particularly and without limitation, this news release contains forward-looking statements concerning: the timing and ability of the Company to advance the Ima Mine to production. There can be no assurance that such statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Mineral Resources are not mineral reserves and do not have demonstrated economic viability. Mineral resources do not take into account factors such as mineability, mining selectivity, mining losses, or dilution. These estimates include inferred mineral resources, which are considered too speculative geologically for economic factors to be applied in a manner that would support their categorization as mineral reserves. Furthermore, there is no assurance that inferred mineral resources will be converted to the measured and indicated categories through additional drilling, or ultimately categorized as mineral reserves once economic considerations have been applied. Statements concerning historical mineral resources, historical reserves, production, and exploration results on the property have been obtained through both public and private sources, and are believed to be substantially factual and relevant in that they demonstrate the tenor of exploration targets on the property. Historical resource estimates and reserves pre-date the implementation of NI 43-101 and do not use categories stipulated by CIM. Prior operators assigned confidence categories which differ from those stipulated by CIM, as they may not have demonstrated economic viability. The estimates should not be relied upon until they have been verified.

Factors that could cause actual results to differ materially from such forward-looking statements are set out in the Company's public disclosure record available on SEDAR+ (www.sedarplus.ca) under the Company's issuer profile. Readers are further cautioned not to place undue reliance on any forward-looking statements, as such information, although considered reasonable by the management of the Company at the time of preparation, may prove to be incorrect and actual results may differ materially from those anticipated.

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this news release. No stock exchange, securities commission or other regulatory authority has approved or disapproved the information contained herein.

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