Stillwater Critical Minerals announced an updated NI 43-101 mineral resource estimate for the Stillwater West critical minerals project in a news release dated August 27, 2026. The full technical report is available on the Company’s profile on www.sedar.com.

Stillwater West 2026 NI 43-101 Technical Report - View PDF

2026 Mineral Resource Estimate

TABLE 1 – Grade at Three NiTEq Cut-off Grades

Stillwater West Indicated and Inferred Mineral Resource Estimates, August 27, 2026

TABLE 2 – Contained Metal at Three NiTEq Cut-off Grades

Stillwater West Indicated and Inferred Mineral Resource Estimates, August 27, 2026

Notes to accompany Mineral Resources Estimates presented in Tables 1 and 2:

1. Mineral Resources are reported within a constraining pit shell using the 2014 CIM Definition Standards.
2. Mineral Resources have an effective date of August 27, 2026. The Qualified Person for the estimate is Mr. Timothy O. Kuhl, RM SME, of Mine Technical Services.
3. A NiTEq is used for reporting Mineral Resources. NiTEq base case cutoff is 0.20%. The NiTEq is determined based on metal prices of US$8.00/lb for Ni, US$4.50/lb for Cu, US$11.00/lb for Co, US$1250.00/oz for Pt, US$1250.00/oz for Pd, US$3000.00/oz for Au and US$6500/oz for Rh.  Recoveries of 80% were used for Ni, Co, Pt, Pd, Au, Rh and the Cu recovery used was 85%.  NiTEq% is calculated based on the above metal prices and recoveries, resulting in NiTEq = Ni% + (Cu% × 0.598) + (Co% × 1.375) + (Pt g/t × 0.228) + (Pd g/t × 0.228) + (Au g/t × 0.547) + (Rh g/t × 1.185).
4. Open pit mining is assumed.  Assumptions used to develop pit shell include: mining cost of $2.50/t and a processing cost of $18/t of ore.  The processing cost includes costs for G&A, smelter and shipping charges.  A 50° pit slope is assumed.
5. Tonnage and grade estimates are in metric units. 
6. Mineral Resource tonnage and contained metal have been rounded to reflect the accuracy of the estimate, and numbers may not add due to rounding.
7. Equivalent contained metal and grades do not include Cr.
8. There are no legal, political, environmental or other risks known to the Qualified Persons consider would materially affect the Mineral Resource estimates.

The 2026 MRE incorporates new drilling, selected historical drilling, refined geological interpretation and structural modelling. The estimate was prepared by Mr. Tim Kuhl of Mine Technical Services (“MTS”), an independent Qualified Person, in accordance with National Instrument 43-101. Mr. Kuhl and his team gained significant experience with Platreef-style mineralization during their time at Wood, AMEC Foster Wheeler, and AMEC and over the past two decades working under the late Dr. Harry Parker. This experience informed the approach applied to the thick mineralized zones of the Stillwater West project, where dynamic anisotropy search geostatistical techniques using locally varying anisotropy were applied across the different structural domains identified in the updated geological model. This is the first time this approach has been used at Stillwater West. There are no known legal, political, environmental or other risks that the Qualified Persons consider could materially affect the potential development of the Mineral Resources.

The updated estimate incorporates 14 new drill holes (5,781 meters) from the 2023 and 2025 drilling campaigns as well as historic drillholes not included in the previous Mineral Resource estimate as a result of detailed QA/QC review. Dr. Ted Eggleston, P.Geo., of MTS, a Qualified Person who is also independent of the Company, verified the current and historical assay and geological data through a detailed review of QA/QC information and original laboratory certificates. The Qualified Persons also conducted two field visits to the Stillwater drill sites and core facility. The Qualified Persons reviewed the historical metallurgical data and benchmarking information provided by the Company on analogue deposit metallurgical performance, and reviewed information provided by the Company on aspects of mineral claims, surface rights, royalties, permitting and environmental considerations.  The Qualified Persons identified no material limitations in the data verification process that would affect the Mineral Resource estimate.