Amount of annual advance payments by the entity from fifth anniversary until the commencement of commercial production.

No definition available.

Name:	gmtl_AdvanceRoyaltyPaymentAnnualAmountFromFifthAnniversaryUntilCommencementOfCommercialProduction
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of option to purchase leased claims, before deduction of annual payments made

+ References

No definition available.

+ Details

Name:	gmtl_AmountOfOptionToPurchaseLeasedClaimsBeforeDeductionOfAnnualPaymentsMade
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of annual lease payments to be made by the entity for leased mining claims.

+ References

No definition available.

+ Details

Name:	gmtl_AnnualLeasePaymentsForMiningClaims
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Annual non-refundable prepayments receivable

+ References

No definition available.

+ Details

Name:	gmtl_AnnualNonRefundablePrepaymentsReceivable
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Commitment for annual vehicle management costs and claim related fees

+ References

No definition available.

+ Details

Name:	gmtl_CommitmentForAnnualVehicleManagementCostsAndClaimRelatedFees
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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:	gmtl_DisclosureOfCapitalCommitmentsLineItems
Namespace Prefix:	gmtl_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum percentage of the earn-in option available to the entity, as operator, to increase its ownership interest in the project.

+ References

No definition available.

+ Details

Name:	gmtl_MaximumEarnInOptionAsOperatorPercentage
Namespace Prefix:	gmtl_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of semi-annual payment committed by the entity for a mining project.

+ References

No definition available.

+ Details

Name:	gmtl_MiningProjectSemiAnnualPaymentCommitmentAmount
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of liabilities assumed by the entity in connection with the assignment and assumption agreement.

+ References

No definition available.

+ Details

Name:	gmtl_OptionAgreementLiabilitiesAssumed
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage of interest to be acquired under an agreement.

+ References

No definition available.

+ Details

Name:	gmtl_PercentageOfInterestToBeAcquired
Namespace Prefix:	gmtl_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of ownership interest held in the projects.

+ References

No definition available.

+ Details

Name:	gmtl_PercentageOfOwnershipInterestHeld
Namespace Prefix:	gmtl_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of royalty held.

+ References

No definition available.

+ Details

Name:	gmtl_PercentageOfRoyaltyHeld
Namespace Prefix:	gmtl_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of royalty that may be repurchased

+ References

No definition available.

+ Details

Name:	gmtl_PercentageOfRoyaltyThatMayBeRepurchased
Namespace Prefix:	gmtl_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Period for buy-back of royalty after commencement of production

+ References

No definition available.

+ Details

Name:	gmtl_PeriodForBuyBackOfRoyaltyAfterCommencementOfProduction
Namespace Prefix:	gmtl_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount payable by the entity to buy back the royalty within the specified period following commencement of production.

+ References

No definition available.

+ Details

Name:	gmtl_RoyaltyBuyBackPrice
Namespace Prefix:	gmtl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Yearly maintenance claim fees paid

+ References

No definition available.

+ Details

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

- Details

Name:	ifrs-full_ClassesOfAssetsAxis=gmtl_PilotMountainProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	ifrs-full_ClassesOfAssetsAxis=gmtl_GarfieldProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	ifrs-full_ClassesOfAssetsAxis=gmtl_PilotMountainNorthProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfAssetsAxis=gmtl_StonewalProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfAssetsAxis=gmtl_KibbyBasinProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfAssetsAxis=gmtl_WhiteElephantProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfAssetsAxis=gmtl_CinchProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfAssetsAxis=gmtl_TempiuteProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	ifrs-full_ClassesOfAssetsAxis=gmtl_GolcondaProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

Name:	ifrs-full_ClassesOfAssetsAxis=gmtl_KibbyBasinPilotNorthWhiteElephantAndCinchProjectsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Capital commitments (Details) - USD ($)		12 Months Ended
Capital commitments (Details) - USD ($)	May 21, 2021	Jun. 30, 2026	Jan. 31, 2025	Nov. 01, 2021	Jun. 17, 2021	May 20, 2021
Pilot Mountain
Capital commitments
Ownership interest held, percentage		100.00%
Commitment for annual vehicle management costs and claim related fees		$ 80,000
Pilot Mountain \| Nevada Select Royalty
Capital commitments
Percentage of royalty held				2.00%
Annual non-refundable prepayments receivable				$ 40,000
Garfield
Capital commitments
Ownership interest held, percentage		100.00%
Commitment for annual vehicle management costs and claim related fees		$ 45,000
Garfield \| Sunrise Resources Group
Capital commitments
Percentage of royalty that may be repurchased					1.00%
Royalty buy-back price					$ 1,000,000
Garfield \| Sunrise Resources Group
Capital commitments
Percentage of royalty held					2.00%
Pilot Mountain North
Capital commitments
Ownership interest held, percentage		100.00%
Stonewall
Capital commitments
Ownership interest held, percentage		100.00%
Commitment for annual vehicle management costs and claim related fees		$ 4,000
Stonewall \| Sunrise Resources Group
Capital commitments
Percentage of royalty that may be repurchased					1.00%
Royalty buy-back price					$ 1,000,000
Stonewall \| Sunrise Resources Group
Capital commitments
Percentage of royalty held					2.00%
Kibby Basin
Capital commitments
Ownership interest held, percentage		100.00%
White Elephant
Capital commitments
Ownership interest held, percentage		100.00%
Cinch
Capital commitments
Ownership interest held, percentage		100.00%
Tempiute
Capital commitments
Maximum earn-in option, percentage		100.00%	100.00%
Commitment for annual vehicle management costs and claim related fees		$ 60,000
Tempiute \| Owner of Tempiute
Capital commitments
Semi-annual payment commitment			$ 25,000
Advance royalty payment on fifth and each succeeding anniversary until commencement of commercial production			$ 25,000
Golconda Summit
Capital commitments
Maximum earn-in option, percentage	100.00%	100.00%
Annual lease payments	$ 50,000
Amount of option to purchase leased claims, before deduction of annual payments made	335,000
Commitment for annual vehicle management costs and claim related fees		$ 10,000
Golconda Summit \| Eureka Resources
Capital commitments
Liabilities assumed	$ 275,000
Percentage of royalty that may be repurchased	1.00%
Period for buy-back of royalty after commencement of production	1 year
Royalty buy-back price	$ 1,000,000
Golconda Summit \| GR Silver Mining \| Eureka Resources
Capital commitments
Percentage of interest to be acquired						100.00%
Golconda Summit \| Eureka Resources
Capital commitments
Percentage of royalty held	1.00%
Kibby Basin, Pilot North, White Elephant and Cinch Projects
Capital commitments
Yearly maintenance claim fees paid		$ 35,000