Nechalacho Basal Zone selected for Canada Investment Summit prospectus

Toronto, Ontario--(Newsfile Corp. - September 15, 2026) - Avalon Advanced Materials Inc. (TSX: AVL) (OTCQB: AVLNF) ("Avalon" or the "Company") is pleased to announce that its Nechalacho Rare Earths Project ("Nechalacho") in the Northwest Territories has been selected for inclusion in the Canada Investment Summit Prospectus and will be showcased by the Government of the Northwest Territories ("GNWT") as a strategic critical minerals development opportunity.

The inaugural Canada Investment Summit, hosted by the Government of Canada in partnership with Canada's major institutional investment organizations, is bringing together global investors and Canadian companies to highlight investment opportunities across the country. The Summit's official prospectus features 167 investment opportunities, including 63 projects in the minerals and metals sector, providing Nechalacho with exposure to international investors seeking opportunities across Canada's strategic resource industries.

Nechalacho's inclusion provides an important national and international platform to showcase both the project and the Northwest Territories' broader critical minerals potential. Premier R.J. Simpson and the GNWT are highlighting Nechalacho as one of the territory's key resource development opportunities, positioning the project among a select group of Canadian rare earth and critical minerals projects being presented to global investors at the Summit.

The selection comes as governments in Canada, the United States and allied markets increasingly focus on establishing secure, diversified supply chains for critical minerals. It also highlights the important role the Northwest Territories can play in strengthening Canada's domestic supply of critical minerals while creating opportunities for investment, economic development and long-term benefits for the territory.

Nechalacho is one of Canada's most advanced undeveloped rare earth assets, benefiting from substantial historical technical work, including a historical 2013 Definitive Feasibility Study, extensive drilling and supporting technical studies. Avalon recently announced an updated Mineral Resource Estimate for the Basal Zone prepared in accordance with U.S. SEC S-K 1300 requirements, providing an updated technical foundation for the project as the Company advances its U.S. listing and capital markets strategy.

Avalon is also advancing a Preliminary Economic Assessment intended to modernize the development and processing approach contemplated in the historical feasibility study and evaluate the project's economics. The work forms part of Avalon's broader strategy to advance Nechalacho toward development while evaluating potential processing pathways, strategic partnerships and financing opportunities.

Avalon believes Nechalacho's scale, advanced technical foundation, exposure to both light and heavy rare earth elements and location within a stable Canadian jurisdiction position the project as a compelling opportunity within North America's critical minerals industry.

About Avalon Advanced Materials Inc. Avalon Advanced Materials Inc. is a Canadian critical minerals company focused on advancing lithium and rare earth elements—two of the fastest-growing segments of the global energy transition. The Company is developing strategic assets to participate in high-growth markets and support the build-out of secure North American supply chains. Avalon is advancing the Nechalacho Rare Earth Elements and Zirconium Project in the Northwest Territories, which contains all light and heavy rare earth elements, as well as zirconium, tantalum, and niobium—critical minerals used in advanced technologies across the communications, defense, advanced technologies, and energy sectors. The Company is also focused on vertically integrating the Ontario lithium supply chain through the development of Lake Superior Lithium Inc., Ontario's first midstream lithium hydroxide processing facility, located in Thunder Bay. This facility is expected to serve as a cornerstone of North America's integrated battery materials supply chain, transforming northern Ontario lithium into essential inputs for transportation, grid storage, and advanced manufacturing.