Sally Malay had been earning a 60% interest in the project by completing a feasibility study based on mining the near surface mineralisation. Copernicus contains around 359,000 tonnes grading 1.3% nickel, 0.7% copper and 0.05% cobalt.

Thundelarra director of exploration Brian Richardson told MiningNews.net Thundelarra was not happy with the amount of drilling conducted.

“They presented us the document in January and Thundelarra’s board has decided that we do not think it is a comprehensive feasibility study document and we haven’t accepted it,” Richardson said.

“We didn’t think there was enough metallurgy or drilling done to make a decision to mine. We were not confident to go ahead into a mining venture with the data available.”

Thundelarra was also worried by the undisclosed cost estimates of the project, according to Richardson.

“It [feasibility study] gave cost estimates but we didn’t think they were tight enough. Sally Malay were keen to start mining but we weren’t so keen – we wanted more of a guarantee of the costs.”

Sally Malay managing director Peter Harold was en route to China and told MiningNews.net he would not comment until the company had formulated an official response.

The original plan had been to develop the project to coincide with Sally Malay taking its namesake project, 35km to the north, underground. Ore from Copernicus was to be processed at the Sally Malay plant and Richardson said this would still be a processing option down the track.

Thundelarra has made immediate plans to start drilling itself at the project, with a 2000m campaign planned.

“Our intention is to complete what Sally Malay started, to chase the Copernicus Deeps where we think there is potential for large deposit, to complete the infill drilling that Sally Malay started on Copernicus North and define a resource there,” he said.

Thundelarra would also consider other potential joint venture partners with LionOre Mining an obvious possibility. LionOre and Thundelarra already have a regional joint venture with LionOre earning 60% by spending $5 million over five years at the East Kimberly tenement.

Richardson said he would not rule out future agreements with Sally Malay, which held a trump card in its Sally Malay plant.

Thundelarra also has been exploring at the East Kimberly projects itself, including at the Lamboo gold project.

Thundelarra shares were unchanged at the close of trade at 26c, while Sally Malay shares slid over 6% to 83c.