Prepaid Expenses and Project Deposits - Schedule of Movement of Project Deposits (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2026 USD ($)
Prepaid Deposit [Roll Forward]
Project deposit, beginning balance	$ 0
Advances paid	14,383
Transferred to construction in progress	(973)
Recognized in expense	(796)
Project deposit, ending balance	12,614
Pilot HREE Metallization
Prepaid Deposit [Roll Forward]
Project deposit, beginning balance	0
Advances paid	1,315
Transferred to construction in progress	0
Recognized in expense	(315)
Project deposit, ending balance	1,000
Commercial HREE Metallization
Prepaid Deposit [Roll Forward]
Project deposit, beginning balance	0
Advances paid	8,370
Transferred to construction in progress	(973)
Recognized in expense	(281)
Project deposit, ending balance	7,116
SRC REPF Upgrade
Prepaid Deposit [Roll Forward]
Project deposit, beginning balance	0
Advances paid	3,898
Transferred to construction in progress	0
Recognized in expense	(200)
Project deposit, ending balance	3,698
Supply agreement
Prepaid Deposit [Roll Forward]
Project deposit, beginning balance	0
Advances paid	800
Transferred to construction in progress	0
Recognized in expense	0
Project deposit, ending balance	$ 800