RETRANSMISSION: Sienna More Than Doubles its Acreage Bordering Cameco Corporation in the Athabasca Basin of Saskatchewan

Vancouver, August 21, 2024 - Sienna Resources Inc. (TSXV: SIE) (OTC Pink: SNNAF) (FSE: A1XCQ0) ("Sienna" or the "Company") is pleased to announce that it has more than doubled its acreage on the Dragon Uranium Project directly bordering Cameco Corporation (CCO) in the world-class uranium district of the Athabasca Basin. This project now consists of 23,134 contiguous acres. Sienna Resources' management cautions that past results or discoveries on properties in proximity to Sienna Resources may not necessarily be indicative of the presence of mineralization on the company's properties. Management is formulating plans for the Athabasca Basin Uranium projects.

Jason Gigliotti, President of Sienna Resources Inc., stated, "We are very pleased to significantly increase our acreage directly bordering Cameco Corporation (CCO.t) in the Athabasca Basin. The Athabasca Basin is world renowned as the world's highest grade uranium district and home to many of the world's largest and highest grade uranium discoveries. There has been a renewed interest in uranium recently as the USA's first new major uranium project in 30 years has just come on line in Georgia. Sienna also just increased its landholdings bordering Ramp Minerals Inc in Saskatchewan. Sienna is one of the larger landholders in this exciting new gold mining camp and with Eric Sprott taking a major stake in the area it shows the promises of this new potentially world-class mining district. Sienna management is currently developing plans to move forward on this large sized new gold project at a time when gold is at all-time highs. Sienna is coming into a very active period and management is very optimistic about the short and long term growth drivers in place now."

Recently (July 22, 2024), Sienna significantly increased its acreage on the Stonesthrow Gold Project in Saskatchewan now consisting of approximately 18,350 contiguous acres prospective for gold directly bordering Ramp Metals Inc (RAMP). Ramp announced (June 17, 2024) multiple zones of gold mineralization, including 73.55 grams per tonne gold and 19.50 grams per tonne silver. Ramp has just announced a strategic investment led by Eric Sprott for the drilling of this prospect. Sienna Resources' management cautions that past results or discoveries on properties in proximity to Sienna Resources may not necessarily be indicative of the presence of mineralization on the company's properties.

Recently, (May 23, 2024) Sienna acquired Case Lake West Cesium and Spodumene Pegmatite Project in the Larder Lake Mining division of Ontario, Canada, roughly 100 km north of Kirkland Lake, NE Ontario. This project consists of approximately 2,200 contiguous acres prospective for Cesium and Spodumene Pegmatites directly bordering Power Metals Corp's (PWM) Case Lake cesium and pegmatite swarm discovery. On May 22, 2024 Power Metals announced "WORLD-CLASS CESIUM RESULTS UP TO 18.13% AT CASE LAKE." This was very exciting news regarding this growing cesium district. Sienna 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.

About Sienna Resources Inc.

Sienna has acquired the "Stonesthrow Gold Project", consisting of approximately 18,350 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 2,200 contiguous acres prospective for Cesium and Spodumene Pegmatites. Sienna has also just acquired the 10,357 acre "Uranium Town Project" bordering Denison Mines Corp., 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 recently expanded the "Elko Lithium Project" in Elko County, Nevada. This project consists of approximately 1840 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 through its new venture, NeoLith Energy in a strategic partnership with Pure Energy. The deployment of the pilot plant will be in Clayton Valley, Nevada, USA. The NeoLith Energy sustainable approach uses a differentiated direct lithium extraction (DLE) process to enable the production of high-purity, battery-grade lithium material while reducing the production time from over a year to weeks. Results from this pilot plant are expected in 2024 and could have a significant impact on the brine prospects within Clayton Valley Nevada as Sienna is located in the deepest section of this brine deposit.

This new acreage was acquired via staking.

Qualified Person:

Mr. Frank Bain, PGeo, 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.

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