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Mineral Rights and Properties, Net - Summary of Mineral Rights and Properties, Net (Parenthetical) (Detail) - USD ($) $ in Thousands | Sep. 30, 2023 | Jun. 30, 2023
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Asset Retirement Cost [Member] |  |
Mineral Properties Net [Line Items] |  |
Asset retirement cost, accumulated amortization | $ 28 | $ 23

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- Definition Mineral properties, accumulated amortization. + References No definition available. + Details
Name: | feam_MineralPropertiesAccumulatedAmortization
Namespace Prefix: | feam_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition Mineral properties net. + References No definition available. + Details
Name: | feam_MineralPropertiesNetLineItems
Namespace Prefix: | feam_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | feam_MineralRightsAndPropertiesAxis=feam_AssetRetirementCostMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |