The epitaph plaque dedicated to father Jakub Kowalski (deceased in 1822) was made of so-called black Dębnik marble.
"Epitaph plaque of father Jakub Kowalski", [in:] "The Sacred Lesser Poland Heritage", 2024, source: https://sdm.upjp2.edu.pl/en/works/epitaph-plaque-of-father-jakub-kowalski