Three actinomycetes (strains HKI 0478(T), HKI 0479 and HKI 0480) isolated from the surfaces of rocks in the Feengrotten medieval alum slate mine (Thuringia, Germany) were examined in a polyphasic taxonomic study. The following morphological and chemotaxonomic features supported their classification as members of the genus Kribbella: the presence of ll-diaminopimelic acid in the cell-wall peptidoglycan; glucose together with minor amounts of mannose and ribose as the whole-cell sugars; polar lipids comprising phosphatidylcholine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and unknown phospho- and glycolipids; fatty acid profiles characterized by the predominance of anteiso-C(15 : 0), iso-C(16 : 0) and C(16 : 0) 9-methyl; and the presence of MK-9(H(4)) as the main menaquinone. The isolates had almost identical 16S rRNA gene sequences (99.9-100 %) and were most closely related to the type strains of Kribbella jejuensis (98.9 % sequence similarity), Kribbella swartbergensis and Kribbella solani (both 98.8 %). A wide range of genotypic and phenotypic markers as well as the low levels of DNA-DNA relatedness between strain HKI 0478(T) and the type strains of K. jejuensis (41.3 %), K. swartbergensis (18.6 %) and K. solani (14.2 %) distinguished the novel strains from their closest phylogenetic neighbours. On the basis of these results, strain HKI 0478(T) represents a novel member of the genus Kribbella, for which the name Kribbella aluminosa sp. nov. is proposed. The type strain is HKI 0478(T) (=DSM 18824(T) =JCM 14599(T)).