George Marino mastered the original 1991 release of Metallica's self-titled album, commonly called The Black Album.
Mastering is the final technical stage that prepares a recorded mix for distribution formats. Marino's credit belongs to the original album, completed after the recording, engineering, production, and mixing work had been finished.
The production credits distinguish several jobs that listeners sometimes combine. Bob Rock produced the album, Randy Staub engineered it, and Mike Tacci served as assistant engineer. Marino handled the original mastering, giving the finished release its final prepared form.
Later editions have different mastering credits. The 2021 anniversary remaster was mastered by Bob Ludwig at Gateway Mastering, so Ludwig is associated with that later edition rather than the original 1991 release. This distinction matters when a question specifies the original album instead of a remaster or deluxe reissue.