Ioneer (ASX:INR) said the Sibanye-Stillwater board decided not to proceed with the Rhyolite Ridge lithium-boron project joint venture in Nevada, allowing the project to progress to a final investment decision, according to a Thursday filing with the Australian bourse.

The unit purchase and subscription agreement with Sibanye-Stillwater has been terminated, the filing said.

Shares were down 9% in afternoon trade Thursday.