v3.26.1
Cover Page - shares
9 Months Ended
Mar. 31, 2026
May 11, 2026
Cover [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Entity Registrant Name 5E ADVANCED MATERIALS, INC.  
Entity Central Index Key 0001888654  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2026  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q3  
Current Fiscal Year End Date --06-30  
Document Transition Report false  
Entity File Number 001-41279  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 87-3426517  
Entity Address, Address Line One 9329 Mariposa Road  
Entity Address, Address Line Two Suite 210  
Entity Address, City or Town Hesperia  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 92344  
City Area Code 442  
Local Phone Number 221-0225  
Title of 12(b) Security Common Stock, $0.01 par value  
Trading Symbol FEAM  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period true  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   41,515,223