Phoenix, Arizona--(Newsfile Corp. - January 16, 2023) - Excelsior Mining Corp. (TSX: MIN) (FSE: 3XS) (OTCQB: EXMGF) ("Excelsior" or the "Company") is pleased to announce that it has entered into a Collaboration Agreement with Nuton LLC, a Rio Tinto venture, to evaluate the use of its Nuton™ copper heap leaching technologies at Excelsior's Johnson Camp mine in Cochise County, Arizona.

Rio Tinto has developed the Nuton technologies, an extensive portfolio of advanced copper heap leaching technologies targeted at primary sulfide minerals (including lower grade minerals), which could not otherwise be processed using traditional leaching or sulfide processing technologies. These technologies offer the potential to produce additional copper in a cost-effective manner that has significant environmental benefits and reduces waste from new and ongoing operations.

The first stage of the collaboration involves Nuton completing certain test work on materials collected from the Company's Johnson Camp mine project to confirm that suitable conditions exist to deploy the Nuton technologies. Assuming this test work is successful, the parties would then work toward negotiating commercial terms for a full-scale deployment of the Nuton technologies at the Johnson Camp mine. Test work is expected to commence during the first quarter of 2023 with a view toward potentially negotiating commercial terms dependent on the test results and other factors during the third quarter of 2023.

ABOUT NUTON

Nuton is an innovative new venture that aims to help grow Rio Tinto's copper business. At the core of Nuton is a portfolio of proprietary copper leach related technologies and capability – a product of almost 30 years of research and development. The Nuton technologies offer the potential to economically unlock known low-grade copper sulfide resources, copper bearing waste and tailings, and achieve higher copper recoveries on oxide and transitional material, allowing for a significantly increased copper production outcome. One of the key differentiators of Nuton is the potential to deliver leading environmental performance, including more efficient water usage, lower carbon emissions, and the ability to reclaim mine sites by reprocessing mine waste.

ABOUT EXCELSIOR MINING

Excelsior "The Copper Solution Company" is a mineral exploration and production company that owns and operates the Gunnison Copper Project in Cochise County, Arizona. The project is a low cost, environmentally friendly in-situ recovery copper extraction project that is permitted to 125 million pounds per year of copper cathode production. Excelsior also owns the past producing Johnson Camp Mine and a portfolio of exploration projects, including the Peabody Sill and the Strong and Harris deposits.

For more information on Excelsior, please visit our website at www.excelsiormining.com