Avalon updates mineral resource estimate for Nechalacho Basal Zone

First Comprehensive Refresh of Mineral Resource and Economic Framework of Nechalacho Basal Zone Since 2013, Establishing a Current Technical Foundation Under S-K 1300

58.6 million tonnes of Measured and Indicated resources grading 1.49% TREO, plus 130.6 million tonnes of Inferred resources grading 1.31% TREO

Updated mineral resources incorporate current economic assumptions and US$366.40/t Net Metal Revenue ("NMR") cut-off in assessing reasonable prospects for economic extraction

Neodymium, praseodymium, dysprosium and terbium account for approximately 88% of estimated in-situ REO value, highlighting Nechalacho's exposure to magnet-critical rare earth elements

Toronto, Ontario--(Newsfile Corp. - August 6, 2026) - Avalon Advanced Materials Inc. (TSX: AVL) (OTCQB: AVLNF) ("Avalon" or the "Company") is pleased to announce the completion of an updated Mineral Resource Estimate ("MRE") for the wholly-owned Basal Zone of the Nechalacho Rare Earth Elements Project ("Nechalacho" or the "Project"), located approximately 110 kilometers southeast of Yellowknife, Northwest Territories. The Basal Zone is a deeper mineralized zone underlying the near-surface Upper Zone and formed the basis of the Company's 2013 Definitive Feasibility Study ("DFS") prepared under Canadian National Instrument 43-101 - Standards of Disclosure for Mineral Projects ("NI 43-101") and CIM standards at that time.

The updated MRE was independently prepared by Micon International Limited ("Micon"), which applied current geological, mining, metallurgical and economic assumptions to develop the mineral resource estimate. Micon also serves as the independent Qualified Person for the estimate. The MRE represents the first comprehensive re-estimation of Nechalacho's Basal Zone mineral resource since