Significant Accounting Policies (Details) - USD ($)	3 Months Ended	12 Months Ended	13 Months Ended
Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2022	Sep. 03, 2021
Cash	$ 376,677	$ 954,974	$ 376,677
Cash equivalents	0	0	0
Federal depository insurance coverage	250,000
Borrowings under promissory note	0	0	167,251
Outstanding balance of advances from related parties	0	0	0
Advances from related parties	0		150,000
Unrecognized tax benefits	0	0	0
Unrecognized tax benefits accrued for interest and penalties	0	0	0
Marketable securities held in Trust Account	265,173,033	$ 265,155,619	265,173,033
IPO Member
Offering cost	26,713,571		26,713,571
Underwriting fees	5,302,956		5,302,956
Deferred underwriting fees	9,280,173		9,280,173
Other offering costs	1,022,789		1,022,789
Offering cost included in stockholders equity	24,729,441
Over-allotment option
Underwriting fees				$ 302,956
Deferred underwriting fees				$ 530,173
Anchor Investors
Investments fair value	11,107,653		11,107,653
Anchor Investors \| IPO Member
Investments fair value	11,107,653		11,107,653
Warrants
Offering cost	1,984,130		1,984,130
Warrants \| IPO Member
Offering cost	$ 1,984,130		$ 1,984,130
Private Placement Warrants \| IPO Member
Number of warrants	13,666,666
Private Placement Warrants \| Over-allotment option
Number of warrants	201,971
Public Warrants \| Over-allotment option
Number of warrants	504,927

The carrying value as of balance sheet date of underwriting compensation deferred, classified as noncurrent.

No definition available.

Name:	mtal_DeferredUnderwritingCompensationNoncurrent
Namespace Prefix:	mtal_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This amount represents the federal depository insurance coverage.

+ References

No definition available.

+ Details

Name:	mtal_FederalDepositoryInsuranceCoverage
Namespace Prefix:	mtal_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of new units issued to underwriters during the period.

+ References

No definition available.

+ Details

Name:	mtal_NumberOfUnitsIssuedToUnderwritersDuringPeriod
Namespace Prefix:	mtal_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The amounts of proceeds advances from related parties.

+ References

No definition available.

+ Details

Name:	mtal_ProceedsAdvancesFromRelatedParties
Namespace Prefix:	mtal_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the amount of other offering costs incurred.

+ References

No definition available.

+ Details

Name:	mtal_SaleOfStockOtherOfferingCosts
Namespace Prefix:	mtal_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of offering fees incurred and paid for underwriters.

+ References

No definition available.

+ Details

Name:	mtal_SaleOfStockUnderwritingFees
Namespace Prefix:	mtal_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of transaction costs incurred.

+ References

No definition available.

+ Details

Name:	mtal_TransactionCosts
Namespace Prefix:	mtal_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of decrease in additional paid in capital (APIC) resulting from direct costs associated with issuing stock. Includes, but is not limited to, legal and accounting fees and direct costs associated with stock issues under a shelf registration.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

+ Details

Name:	us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of cash, securities, or other assets held by a third-party trustee pursuant to the terms of an agreement which assets are available to be used by beneficiaries to that agreement only within the specific terms thereof and which agreement is expected to terminate more than one year from the balance sheet date (or operating cycle, if longer) at which time the assets held-in-trust will be released or forfeited.

+ References

+ Details

Name:	us-gaap_AssetsHeldInTrustNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
-Section 45
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=118262064&loc=SL116631418-115840

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
-Section 45
-Paragraph 21
-URI http://asc.fasb.org/extlink&oid=118262064&loc=SL116631419-115840

+ Details

Name:	us-gaap_Cash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_CashEquivalentsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of obligations due all related parties.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(1))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(C))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(5))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.17)
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iv))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iii)(B))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(5))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15(3),(4))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

+ Details

Name:	us-gaap_DueToRelatedPartiesCurrentAndNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

+ Details

Name:	us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow for a loan, supported by a promissory note, granted to related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3213-108585

+ Details

Name:	us-gaap_OriginationOfNotesReceivableFromRelatedParties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 10B
-URI http://asc.fasb.org/extlink&oid=123427490&loc=SL37586934-109318

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=SL6600010-109319

+ Details

Name:	us-gaap_UnrecognizedTaxBenefits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32718-109319

+ Details

Name:	us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_IPOMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_OverAllotmentOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=mtal_AnchorInvestorsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=us-gaap_WarrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=mtal_PrivatePlacementWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=mtal_PublicWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: