The AIM-traded firm said Tolsa would start work this week on up to two kilometres of excavator trenching, to better expose and sample the mapped sepiolite deposits.
On 28 June, Sunrise granted Tolsa a six-month option to purchase the Pioche Project for $1.25m, and an ongoing payment to Sunrise of a 3% royalty.
It said the option could be extended for a further 12 months on payment of $50,000 to Sunrise within the option period.
Tolsa is a US-based subsidiary of Tolsa SA, the world's largest producer of sepiolite.
“We are pleased to see that the permitting has proceeded smoothly and in a timely manner and that Tolsa is now proceeding immediately with its proposed exploration programme, having already identified multiple horizons of sepiolite at the Pioche Project,” said executive chairman Patrick Cheetham.
“The trenching programme will provide further exposures of the sepiolite beds to enable a better evaluation of their thicknesses and quality.
“Whilst our focus remains on the CS and Hazen pozzolan projects, the Pioche Project exemplifies the company's long-standing strategy to identify overlooked mineral opportunities and convert these into cash and free carried royalty interests such as those the company already holds on the Junction, Garfield and Stonewall exploration projects.”
At 1315 BST, shares in Sunrise Resources were down 4% at 0.12p.
Reporting by Josh White at Sharecast.com.