UNAUDITED CONDENSED STATEMENT OF OPERATIONS (Parenthetical)	Mar. 31, 2021 shares
Class B ordinary shares \| Over-allotment option
Maximum Common Stock, 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