Commitments and Contingencies	12 Months Ended
Jun. 30, 2026
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	14. Commitments and Contingencies Purchase Obligations As of June 30, 2026, the Company had purchase order commitments of approximately $3.0 million primarily for drilling, services and consultants related to the Company’s wellfield development program, raw materials for the operation of the SSF, engineering services and vendor testing related to the design of the proposed commercial-scale facility, environmental testing and other corporate services. Litigation Construction Services On July 17, 2023, the Company filed a complaint (the “Complaint”) against a previous construction contractor in the United States District Court for the Central District of California, Eastern Division, alleging, among other things, breaches by the contractor of its contractual obligations to 5E Boron Americas under the Procurement and Construction Contract, effective April 26, 2022, relating to the construction of the SSF. On August 10, 2023, the contractor filed an answer to the Complaint and asserted counterclaims against 5E Boron Americas seeking relief of approximately $5.5 million. On March 17, 2026, the parties executed a settlement agreement resolving all claims and counterclaims related to the matter, and the Company paid a settlement amount of approximately $4.3 million. The Company had previously accrued $2.8 million related to probable amounts owed under the construction contract and, upon approval of the settlement, recorded an additional $1.5 million to property, plant and equipment, which will be depreciated prospectively over the remaining useful life of the SSF. Refer to Note 4-Properties, Plant and Equipment, Net for additional details. Mining Claims On May 11, 2026, Elementis Specialties Inc. (“Elementis”) filed a complaint in the United States District Court for the Central District of California, Eastern Division, captioned Elementis Specialties Inc. v. 5E Advanced Materials, Inc. et al., Case No. 5:26-cv-02488, against the Company and its wholly owned subsidiary, 5E Boron Americas. The complaint alleges, among other things, claims for quiet title, trespass, declaratory relief, slander of title, and violation of California’s unfair competition law relating to certain federal unpatented mining claims in San Bernardino County, California. Elementis seeks declaratory and injunctive relief, quiet title, compensatory and consequential damages in an amount to be proven at trial, punitive damages, statutory penalties, attorneys’ fees, costs, and interest. The Company believes it has defensible claims, disputes the allegations, and intends to vigorously defend the matter. On July 31, 2026, the Company filed a counterclaim against Elementis seeking a declaration of the parties’ rights to maintain their respective mining claims. The matter is currently in the discovery stage. A jury trial date has been set for October 2027. Based on information currently available and management’s current assessment, the Company is unable to reasonably estimate possible damages or a range of possible damages and has not recorded an accrual related to this matter in the accompanying consolidated financial statements.

Commitments and Contingencies

12 Months Ended

Jun. 30, 2026

Commitments and Contingencies Disclosure [Abstract]

14. Commitments and Contingencies

Purchase Obligations

As of June 30, 2026, the Company had purchase order commitments of approximately $3.0 million primarily for drilling, services and consultants related to the Company’s wellfield development program, raw materials for the operation of the SSF, engineering services and vendor testing related to the design of the proposed commercial-scale facility, environmental testing and other corporate services.

Litigation

Construction Services

On July 17, 2023, the Company filed a complaint (the “Complaint”) against a previous construction contractor in the United States District Court for the Central District of California, Eastern Division, alleging, among other things, breaches by the contractor of its contractual obligations to 5E Boron Americas under the Procurement and Construction Contract, effective April 26, 2022, relating to the construction of the SSF. On August 10, 2023, the contractor filed an answer to the Complaint and asserted counterclaims against 5E Boron Americas seeking relief of approximately $5.5 million.

On March 17, 2026, the parties executed a settlement agreement resolving all claims and counterclaims related to the matter, and the Company paid a settlement amount of approximately $4.3 million. The Company had previously accrued $2.8 million related to probable amounts owed under the construction contract and, upon approval of the settlement, recorded an additional $1.5 million to property, plant and equipment, which will be depreciated prospectively over the remaining useful life of the SSF. Refer to Note 4-Properties, Plant and Equipment, Net for additional details.

Mining Claims

On May 11, 2026, Elementis Specialties Inc. (“Elementis”) filed a complaint in the United States District Court for the Central District of California, Eastern Division, captioned Elementis Specialties Inc. v. 5E Advanced Materials, Inc. et al., Case No. 5:26-cv-02488, against the Company and its wholly owned subsidiary, 5E Boron Americas. The complaint alleges, among other things, claims for quiet title, trespass, declaratory relief, slander of title, and violation of California’s unfair competition law relating to certain federal unpatented mining claims in San Bernardino County, California. Elementis seeks declaratory and injunctive relief, quiet title, compensatory and consequential damages in an amount to be proven at trial, punitive damages, statutory penalties, attorneys’ fees, costs, and interest. The Company believes it has defensible claims, disputes the allegations, and intends to vigorously defend the matter. On July 31, 2026, the Company filed a counterclaim against Elementis seeking a declaration of the parties’ rights to maintain their respective mining claims. The matter is currently in the discovery stage. A jury trial date has been set for October 2027. Based on information currently available and management’s current assessment, the Company is unable to reasonably estimate possible damages or a range of possible damages and has not recorded an accrual related to this matter in the accompanying consolidated financial statements.