XML 92 R42.htm IDEA: XBRL DOCUMENT
v3.25.2

These consolidated financial statements include the accounts of the Company and the subsidiaries listed in the following table. All intercompany transactions and balances have been eliminated. (Details) | 12 Months Ended |
--- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024
Entity0896800 B C Ltd [Member] |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |
Jurisdiction of incorporation |  | British Columbia, Canada |
Ownership at June 30, 2024 |  | 100.00% | 100.00%
Elk Creek Resources Corp E C R C [Member] |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |
Jurisdiction of incorporation | [1] | Delaware, USA |
Ownership at June 30, 2024 | [1] | 80.42% | 79.70%
Nio Corp Technologies Limited [Member] |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |
Jurisdiction of incorporation |  | United Kingdom |
Ownership at June 30, 2024 |  | 100.00% | 100.00%
[1] | Represents 100% of Class A common stock owned by 0896800, and 3,934,031 and 4,282,116 Vested Shares and 3,391,596 and 3,391,596 Earnout Shares (each as defined below) held by third parties, and outstanding as of June 30, 2025 and 2024, respectively.

X
- Definition The element represents incorporation state country name. + References No definition available. + Details
Name: | niobf_IncorporationStateCountryName
Namespace Prefix: | niobf_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | srt_OwnershipAxis=niobf_Entity0896800BCLtdMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_OwnershipAxis=niobf_ElkCreekResourcesCorpECRCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_OwnershipAxis=niobf_NioCorpTechnologiesLimitedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |