Board Change

              17 December 2025

Tertiary Minerals plc

 ("Tertiary" or the "Company")

Board Change

Tertiary Minerals plc (AIM: TYM) announces that Patrick Cheetham, founder and Executive Chairman, will assume the position of Non-Executive Chairman of the Company with effect from 1 January 2026.

Patrick founded Tertiary, listed the company on AIM in 1999 and has led the Company throughout its 26-years, through several commodity cycles and mineral discoveries, to its present focus on precious and energy transitional metals in Zambia, Nevada (USA) and Sweden.

The change is part of the Company's ongoing development following the appointment of Dr Richard Belcher as Managing Director in March 2025. The Company remains committed to exploration excellence and advancement across its exploration portfolio, including its recent silver-copper-zinc discovery in Zambia.

Richard Belcher, Managing Director of Tertiary Minerals plc, commented:

"Patrick founded the company back in 1999 and has led the company since then, initially as an industrial/critical minerals explorer in Europe, through its expansion into precious metals in the USA and, more recently, the expansion into Zambia. We are thankful to Patrick for his role in founding the Company and leading it for many years, and we are pleased that he will continue to contribute to the Company as Non-Executive Chairman as the Company continues to advance its portfolio of exciting projects."

Patrick Cheetham, Executive Chairman of Tertiary Minerals plc, commented:

"Richard's appointment as Managing Director earlier this year is part of a broader plan to refresh the Company's management team and it is an opportune time for me to make this change. I am confident that the Company is in good hands with a strong portfolio of mineral projects and a clear strategy for growth. It has been a privilege to serve the Company in an executive capacity and I look forward to continuing to Chair the Board going forward."

Further Information:

About Tertiary Minerals plc

Tertiary Minerals plc (AIM: TYM) is an AIM-traded mineral exploration and development company whose strategic focus is on energy transition metals. The Company's projects are all located in stable and democratic, geologically prospective, mining-friendly jurisdictions. Tertiary's current principal activities are the discovery and development of copper and precious metal mineral resources in Zambia and Nevada, USA.