Sienna Resources Inc.: Company Update

• Intersected 2.8 g/t Ag over 6m including 8.3 g/t Ag over 1.5m
• Intersected 0.6 g/t Ag over 36m including 1.0 g/t Ag over 13.5m
• Polymetallic VMS system identified from maiden drill program

Vancouver, British Columbia--(Newsfile Corp. - April 17, 2025) - Sienna Resources Inc. (TSXV: SIE) (OTC Pink: SNNAF) (FSE: A1XCQ0) ("Sienna" or the "Company") wishes to announce that the Company has received results from drill hole assays submitted on its 100% owned Case Lake Project, 80 km east of Cochrane, Ontario. Intersections of silver (Ag) were drilled including: 8.3 g/t Ag over 1.5 m within 6 m of 2.8 g/t Ag from 137 m downhole; 0.6 g/t Ag over 36 m including 1.0 g/t Ag over 13.5 m from 67 m downhole (See Table 1). The drill program successfully identified a polymetallic volcanogenic massive sulphide (VMS) system with intercepts of silver and copper, manganese, and zinc. The company believes that there is potential for a VMS system at the Case Lake property as only 600 m of strike have been tested on the ~2 km long structure.

Figure 1: Plan map of Case Lake drill holes with Ag (g/t) assays (coordinates in WGS84 / UTM Z17N).

To view an enhanced version of this graphic, please visit:
https://images.newsfilecorp.com/files/854/248894_b880a5fec478c87e_002full.jpg

Table 1: Significant intercepts from maiden drill program at the Case Lake Project.

Table 2. Diamond drill hole parameters (WGS84 UTM Zone 17N).

About Sienna Resources Inc.

Sienna has recently significantly increased acreage of the "Stonesthrow Gold Project", consisting now of approximately 31,718 contiguous acres prospective for gold. Sienna has also recently acquired the 7,850 contiguous acres "Case Lake West Project" in Larder Lake Mining division of Ontario, Canada roughly 100 km north of Kirkland Lake, NE Ontario. Sienna has also just acquired the 10,357 acre "Uranium Town Project" bordering Denison Mines Corporation, the now 23,134 contiguous acre "Dragon Uranium Project" bordering Cameco Corporation and the 55,440 acre "Atomic Uranium Project" in the world renowned Athabasca Basin of Saskatchewan. Also, Sienna has the "Elko Lithium Project" in Elko County, Nevada consisting of approximately 1830 contiguous acres directly bordering Surge Battery Metals' "Nevada North Lithium Project" in Elko County, Nevada who announced the highest-grade lithium deposit in the USA. Sienna is also one of the larger landholders in Clayton Valley Nevada. Sienna's Clayton Valley projects include the Blue Clay Lithium Project, the Silver Peak South Project, and the Clayton Valley Deep Basin Lithium Project. Clayton Valley is home to the only lithium production in North America, being Albemarle Corp's Silver Peak deposit. This project is also near Tesla Motors Inc.'s Gigafactory in Nevada. On March 18, 2021, Schlumberger New Energy Venture announced the development of a lithium extraction pilot plant with a strategic partnership with Pure Energy. Management cautions that past results or discoveries on properties in proximity to Sienna may not necessarily be indicative of the presence of mineralization on the company's properties.

We seek Safe Harbor.

Qualified Person:

Curtis Ferron MSc. P.Geo. a qualified person as defined by National Instrument 43-101 has reviewed and approved the scientific and technical disclosure contained within this news release.

If you would like to be added to Sienna's email list, please email info@siennaresources.com for information or join our twitter account at @SiennaResources.

"Jason Gigliotti"
President, Director
Sienna Resources Inc.

Statements in this news release that are not historical facts are forward-looking statements. Forward-Looking statements are statements that are not historical, and consist primarily of projections - statements regarding future plans, expectations and developments. Words such as "expects", "intends", "plans", "may", "could", "potential", "should", "anticipates", "likely", "believes" and words of similar import tend to identify forward-looking statements. Forward-Looking statements in this news release include uncertainty of exploration and development plans regarding the property; commodity price fluctuations; political or economic instability and regulatory changes; currency fluctuations, the state of the capital markets; uncertainty in the measurement of mineral reserves and resource estimates; the Company's ability to attract and retain qualified personnel and management; potential labour unrest; reclamation and closure requirements for mineral properties and the availability of capital to fund the Company's projects, as well as other risks and uncertainties identified under the heading "Risk Factors" in the Company's continuous disclosure documents filed on SEDAR. You are cautioned that the foregoing list is not exhaustive of all factors and assumptions which may have been used. The Company cannot assure you that actual events, performance or results will be consistent with these forward-looking statements, and management's assumptions may prove to be incorrect. These forward-looking statements reflect current expectations regarding future events and operating performance and speak only as of the date hereof and the Company does not assume any obligation to update forward-looking statements if circumstances or management's beliefs, expectations or opinions should change other than as required by applicable law. For the reasons set forth above, you should not place undue reliance on forward-looking statements.

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 press release.

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