UNAUDITED CONDENSED STATEMENTS OF OPERATIONS (Parenthetical)	Jun. 30, 2021 shares
Class B Common Stock \| Over-allotment option
Maximum shares subject to forfeiture	937,500

Represents the maximum number of common stock shares subject to forfeiture.

No definition available.

Name:	mtal_MaximumCommonStockSharesSubjectToForfeiture
Namespace Prefix:	mtal_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant