(Sharecast News) - Shares in tungsten and tin miner Tungsten West were volatile on Wednesday after the Hemerdon mine owner announced the abrupt exit of its chief executive officer.

Neil Gawthorpe has resigned with immediate effect, the company said, without giving a reason for the departure.

The stock was swinging between big gains and losses following the announcement, falling to a low of 4.5p (-10%) by mid-morning after surging to a high of 6p (+20%) initially. By 1148 BST, shares were up 6% at 5.30p.

Chief financial officer Alistair Stobie will step in as a temporary replacement as the board searches for a permanent appointment, the company said in a statement.

"I would like to thank Neil for the progress at the Hemerdon project that has been made under his leadership," said non-executive chair David Cather.

Cather highlighted the right-sizing of the project cost base, lifting of the tonnage cap for truck haulage of aggregates, and obtaining draft permits for a mineral processing facility as notable highlights under Gawthorpe's management.

The environmental permit is the last outstanding permit required for the restart of mining operations at Hermerdon in Devon, which has been out of operation since the 1940s but is thought to hold the second largest tungsten deposit in the world.

"We wish Neil all the best with his future endeavours," Cather said.