A novel selective extraction method on the extraction of Fe and Mn oxides in natural surface coatings (biofilms and associated minerals) was applied to different sets of surface coatings. The results showed that NH 2OH·HCl could extract almost all of the Mn oxides from the surface coatings selectively without significant effect on Fe oxides for all the surface coatings studied. Na 2S 2O 4 can remove Mn oxides more effectively and can remove most of Fe oxides for most surface coatings. The development time and the development environment have little effect on the extraction of Mn oxides. Fe oxides extracted using Na 2S 2O 4 were affected by the characters of the aquatic system to a certain extent.
