Lynas Corp shares have surged following news it submitted a tender in response to the US Department of Defense's call for proposals to build a heavy rare earths separation plant.
The world's only major rare earths producer outside China said in a statement the tender period was not yet closed.
It gave no other details, but Lynas' shares still rose by 5.06 per cent to a near six-week high of $2.49 by 1230 AEDT.
The announcement follows news on Monday that Lynas will build its new $500 million cracking and leaching plant in the historic WA goldmining town of Kalgoorlie.
Reuters on Wednesday had reported the US Army plans to fund construction of rare earths processing facilities in the US, as part of an urgent push by Washington to secure domestic supply of the minerals used to make military weapons and electronics.
The United States is looking to safeguard supplies of rare earths as the protracted trade war with China fuelled concerns that Beijing may look to restrict supply of the key minerals, which has raised the spotlight on Lynas.
Sources familiar with the matter had said the joint venture between Lynas and privately held Blue Line Corp is among the expected respondents to the tender, and responses are due by December 16.
The two firms earlier this year signed a memorandum of understanding to build a rare earth processing facility in Texas.
Other miners mentioned are UCore Rare Metals Inc and Texas Mineral Resources Corp.