The company released a measured resource of 10,500 tonnes of caesium-bearing ore pollucite with a grade of 17.1% caesium oxide, following drilling at the Sinclair caesium zone within the broader project area in January.

Metallurgical testwork on a 25kg composite sample resulted in production of a high density brine which Pioneer said it expected would be confirmed as caesium formate brine.

Caesium formate is used in the production of drilling fluids used in petroleum exploration, with Pioneer managing director David Crook saying the metallurgical testwork had identified a simple process for production of the brine.

Global supply of caesium is largely constrained, the company added, with the metal being mined in small quantities globally.

Canadian specialty chemicals company Cabot Corporation, which completed a pollucite development project at its mine in Manitoba in 2015 – is understood to own substantial portion of the world’s known caesium reserves.

“We are not currently mining at the site and will assess options to access additional reserves in the mine, various technologies to augment our caesium supply and alternative sources of ore as demand for our caesium products warrants,” the company said in its 2016 annual report.

“We believe we have sufficient raw material to enable us to continue to supply caesium products for the foreseeable future, based on our anticipated consumption.”

Because the market is small, there is no active trading of the metal and therefore no official market price for the metal.

Pioneer said it was preparing to collect a bulk sample of pollucite from the Sinclair for larger scale communition and metallurgical testwork, with environmental studies and mine design work currently underway.

Pioneer’s next round of drilling will resume in the June quarter of this year after the company identified other priority caesium and lithium exploration targets.

Shares in the company were down A0.2c to 2.3c in morning trade, valuing the company at 23.9 million.