Tungsten West plc chief executive officer Neil Gawthorpe has resigned with immediate effect, after 15 months in the role.
He remains a board director until finalisation of his settlement agreement.
Chief financial officer Alistair Stobie will become interim CEO and join the board, subject to regulatory checks.
Tungsten West said it had started the process of appointing a permanent CEO.
Non-executive chairman David Cather added: “I would like to thank Neil for the progress at the Hemerdon project that has been made under his leadership, especially in respect of right-sizing the project cost base whilst the updated feasibility study is finalised, obtaining the lifting of the tonnage cap for truck haulage of aggregates, and obtaining the draft environmental permit for the mineral processing facility, the last outstanding permit required for the restart of mining operations.
“We wish Neil all the best with his future endeavours.”
Mr Gawthorpe is also a director of the company’s subsidiary Aggregates West.