AVALON REPORTS ENCOURAGING INITIAL CESIUM ASSAY RESULTS FROM RECENT LILYPAD PROJECT FIELD PROGRAM

September 23, 2021

Toronto, Ontario--(Newsfile Corp. - September 23, 2021) -Avalon Advanced Materials Inc.(TSX: AVL) (OTCQB: AVLNF) ("Avalon" or the "Company") is pleased to announce that it has received initial assay results from grab samples collected during the summer exploration program on the Lilypad Cesium Project located 350 km north of Thunder Bay, Ontario. The new results confirm the exceptional cesium enrichment in several Lithium-Cesium-Tantalum ("LCT") pegmatite dyke occurrences on the property. Cesium is a rare element in growing demand for many new technologies, but with very limited supply following the cessation of mine production from the world's largest historical producer, the Tanco mine, near Bernic Lake, Manitoba.

The work program included line cutting, soil and biogeochemistry grid sampling, as well as geological mapping and sampling over the area of the known LCT pegmatite field (see map on-line athttps://www.avalonadvancedmaterials.com/projects/lilypad/). The soil and biogeochemistry results have not yet been received but are anticipated to indicate directions for extensions of the known pegmatites and identify new pegmatite targets in overburden-covered areas for testing in a future drill program. Additional bulk sampling of the cesium-rich Pollucite Dyke was also carried out and Avalon now has about 400 kg of the pollucite mineralization available for further metallurgical testwork. Sub-samples of the bulk sample assayed at Saskatchewan Research Council averaged 3.02% Cs₂O, 1.07% Li₂O and 0.03% Ta₂O₅, similar to the average grade of the historic resource (below).

Assays of rock samples received to date have confirmed significant cesium values in four LCT dykes on the property with three samples assaying greater than 1% Cs₂O (Table 1). Two of the highest cesium values reported in this work are from the Western Extension of the Pollucite Dyke, about 180 metres west of the closest historic drill hole indicating potential to at least double its strike length. The Pollucite Dyke, with a historic resource estimate^[1]of 340,000 tonnes grading 2.294% Cs₂O and 0.037% Ta₂O₅based on 9 holes drilled to a maximum vertical depth of 250 metres and along a strike length of just 140 metres, remains open for expansion to depth and along strike.

Samples assaying at or greater than 1% Cs₂O were also obtained from the Rubellite Dyke, a second pegmatite with high tantalum enrichment located about 500 metres east of the Pollucite Dyke. Two other little-explored pegmatites known as the Baseline and Opie Dykes were also found to contain significant cesium values (Table 1). Some samples are also highly enriched in lithium where it occurs mainly in coarse grained spodumene. One sample from the Spodumene Dyke with coarse spodumene crystals returned 3.34% Li₂O and the six samples collected averaged 0.7% Li₂O.

Commented President & CEO, Don Bubar, "the Lilypad Cesium Project is proving to be a globally unique example of a large field of cesium-enriched LCT pegmatite dykes with significant resource potential. With cesium continuing to be in very short supply, the Company is now well positioned to help Ontario become the new global leader in cesium production including innovation of new downstream applications."

Once all the geochemical survey results have been received and compiled along with the geological mapping data, next steps will be to plan for a diamond drilling program to test all the new targets including the western extension of the Pollucite Dyke. This work would ideally be scheduled during winter months when access can made via a winter road.

The technical information included in this news release has been reviewed and approved by the Company's Vice President, Operations, Dr. William Mercer, P. Geo (Ont), a Qualified Person under NI 43-101. The field program was supervised by Project Geologist, Sarah Bodeving.

TABLE 1: Selected Individual Rock Analyses

Mineral Zone	Sample	Weight	Cs2O	Li2O	Ta2O5
		kgs	(all in %)
Pollucite Dyke West Extension	B718501	1.12	1.96	1.17	0.06
	B718514	1.11	1.77	1.12	0.07
Rubellite Dyke	B718526	0.34	0.92	0.90	0.01
	B718527	0.60	2.65	1.02	0.01
Spodumene Dyke	B718502	0.73	nsr	1.17	0.02
	B718509	2.55	nsr	3.34	0.01
Baseline Dyke	B718523	0.34	0.54	0.36	0.06
Opie Dyke	B718524	0.28	0.41	0.27	0.16