Vancouver, British Columbia--(Newsfile Corp. - December 12, 2024) - Sienna Resources Inc. (TSXV: SIE) (OTC Pink: SNNAF) (FSE: A1XCQ0) ("Sienna" or the "Company") wishes to provide an update to shareholders on the impact of the strike by the Canadian Union of Postal Workers on the Company's ability to comply with its obligations to deliver to shareholders its financial statements and related disclosure and proxy-related materials in respect of the Company's annual general meeting of shareholders (the "Meeting") scheduled to be held at Cozen O'Connor LLP - 550 Burrard Street, Suite 2501, Vancouver, B.C., on Wednesday, December 18, 2024, at 10 a.m. PST.

Jason Gigliotti, President of Sienna stated, "We are still waiting for our Case Lake drill permit to be approved which we expect shortly. 2025 is shaping up to be a much more active year."

As a result of the strike and pursuant to Canadian Securities Administrators' Co-ordinated Blanket Order 51-931 (Temporary Exemption) from requirements in National Instrument 51-102 (Continuous Disclosure Requirements) and National Instrument 54-101 (Communication with Beneficial Owners of Securities of a Reporting Issuer) to send certain proxy-related materials during a postal strike, the Company is advising shareholders that:

1. At the Meeting, shareholders will be asked to vote on the following matters, all as more particularly described in the Company's management information circular (the "Circular"):
   1. To determine and set the number of directors of the Company at four (4) until the next annual meeting;
   2. To elect directors of the Company to hold office until the next annual meeting;
   3. To appoint Davidson & Company LLP, Chartered Professional Accountants, as the Company's auditor until the next annual meeting and to authorize the directors to set their remuneration;
   4. To consider, and if thought fit, to re-approve the Company's Omnibus Incentive Plan, as described in the Circular;
   5. To transact such further or other business as may properly come before the Meeting or any adjournment or postponement thereof.
2. Electronic versions of the Circular, the form of proxy and all other proxy-related materials, as applicable, have been filed and are available on SEDAR+ and have been posted to the Company's website.
3. The Company has satisfied all of the conditions to rely on, and is relying on, the exemption provided by the blanket order from the requirement to send proxy-related materials to its shareholders.
4. The Company will provide copies of the applicable proxy-related materials by e-mail to each entitled shareholder who requests same while the strike is continuing at no charge. Shareholders should reach out to the Company by e-mail at info@siennaresources.com or by phone at 604-646-6900.
5. If you are a registered shareholder, please contact the Company's transfer agent, Computershare, at generalplanenquiries@computershare.com to submit a request for your individual control number to vote, then contact the Eproxy website to cast your vote for the coming meeting.
6. Beneficial shareholders are shareholders who hold their investment through a brokerage house, depository company or other intermediary. Beneficial shareholders should contact their brokerage house or depository company or other intermediary and ask to obtain their voting control number and the steps of how to vote, which could include Internet voting, completing a form of proxy and e-mailing it, directing your broker over the phone on how you wish to vote, or some other method as described by your brokerage house or depository company. The voting deadline for the Company's coming meeting is 10 a.m. PST on December 16, 2024.

About Sienna Resources Inc.

Sienna has 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 "Case Lake West Cesium and Spodumene Pegmatite Project" in Larder Lake Mining division of Ontario, Canada roughly 100 km north of Kirkland Lake, NE Ontario. This project consists of approximately 7,850 contiguous acres prospective for Cesium and Spodumene Pegmatites. Sienna has also just acquired the 10,357 acre "Uranium Town Project" bordering Denison Mines Corporation (DML, DNN) , the now 23,134 contiguous acre "Dragon Uranium Project" bordering Cameco Corporation (CCO, CCJ) 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' (NILI) "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. On September 10, 2024, SLB announced that the "Nevada demonstration plant integrates direct lithium extraction (DLE), concentration and conversion technologies to sustainably produce lithium at scale with integrated technology solution produces lithium from brine 500 times faster than conventional methods while using significantly less land, water and chemical reagents with a verified results confirm recovery rate of 96% lithium from brine at operational rates." The success that SLB achieved could have a significant future impact on the brine prospects within Clayton Valley Nevada as Sienna is located in the deepest section of this brine deposit. 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.

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.

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.