Reserves (Details) - Dec. 14, 2021 $ in Thousands, $ in Thousands	AUD ($) EquityInstruments company shares	USD ($) EquityInstruments company shares
Reserves
Number of group companies that collapsed \| company	3	3
Intercompany debt recognised as capital contribution on deregistration or liquidation of subsidiaries		$ 5,897
Consideration recharged and capitalised as intangible assets		$ 1,765
Golden Metal Resources Australia Pty Ltd. \| Thor Mining Plc \| Black Fire Industrial Minerals Pty Ltd
Reserves
Number of shares acquired \| shares	1,256,350	1,256,350
Golden Metal Resources Australia Pty Ltd. \| Thor Mining Plc \| BFM Resources Inc.
Reserves
Amount of debt acquired	$ 1,873
Golden Metal Resources Australia Pty Ltd. \| Thor Mining Plc \| Pilot Metals Inc.
Reserves
Amount of debt acquired	$ 2,064
Power Metal Resources Plc \| Thor Mining Plc
Reserves
Consideration paid for acquisition of shares and debt		$ 1,765
Consideration paid for acquisition of shares and debt, ordinary shares \| shares	48,118,920	48,118,920
Consideration paid for acquisition of shares and debt, warrants \| EquityInstruments	12,500,000	12,500,000
Consideration paid for acquisition of shares and debt, cash		$ 115

Amount of debt acquired

No definition available.

Name:	gmtl_AmountOfDebtAcquired
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of consideration paid by third party recharged to the entity.

+ References

No definition available.

+ Details

Name:	gmtl_ConsiderationPaidByThirdPartyRechargedToEntity
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Consideration paid for acquisition of shares and debt

+ References

No definition available.

+ Details

Name:	gmtl_ConsiderationPaidForAcquisitionOfSharesAndDebt
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Consideration paid for acquisition of shares and debt, cash

+ References

No definition available.

+ Details

Name:	gmtl_ConsiderationPaidForAcquisitionOfSharesAndDebtCash
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Consideration paid for acquisition of shares and debt, ordinary shares

+ References

No definition available.

+ Details

Name:	gmtl_ConsiderationPaidForAcquisitionOfSharesAndDebtOrdinaryShares
Namespace Prefix:	gmtl_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Consideration paid for acquisition of shares and debt, warrants

+ References

No definition available.

+ Details

Name:	gmtl_ConsiderationPaidForAcquisitionOfSharesAndDebtWarrants
Namespace Prefix:	gmtl_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of intercompany debt transferred to entity upon deregistration and liquidation of subsidiaries.

+ References

No definition available.

+ Details

Name:	gmtl_DeregistrationOrLiquidationOfSubsidiariesTransferOfIntercompanyDebt
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of shares acquired

+ References

No definition available.

+ Details

Name:	gmtl_NumberOfSharesAcquired
Namespace Prefix:	gmtl_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of subsidiaries deregistered or liquidated.

+ References

No definition available.

+ Details

Name:	gmtl_NumberOfSubsidiariesDeregisteredOrLiquidated
Namespace Prefix:	gmtl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfReservesWithinEquityLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=gmtl_GoldenMetalResourcesAustraliaPtyLtd.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_CounterpartiesAxis=gmtl_ThorMiningPlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=gmtl_BlackFireIndustrialMineralsPtyLtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=gmtl_BfmResourcesIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=gmtl_PilotMetalsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=gmtl_PowerMetalResourcesPlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: