Metal biotransfer is involved in crust formation and can induce exfoliation in building stone as well as the formation of rock varnish often found on petroglyphs, thereby contributing in certain cases to biodeterioration or bioprotection of rocks. The distribution of fungi isolated from different sandstone monuments throughout West Germany was compared to strains isolated from limestone covered by rock varnish in the Negev (Israel). Community composition was determined to be completely different. Manganese (IV) formation could be induced in vitro. The capacity of selected strains to oxidize manganese under laboratory conditions was analyzed quantitatively.