Hydrogen in a natural Pd-O compound from Gongo Soco, Minas Gerais, Brazil

The existence of hydrogen in Pd-O-bearing aggregates, which together with iron oxides form the characteristic dark encrustation of an ouro preto nuggget of Gongo Soco, Minas Gerais, Brazil. is confirmed by elastic recoil detection analysis with a heavy-ion microbeam (micro-ERDA). Hydrogen is lost from Pd-O-bearing areas during the micro-analyses, but not from goethite. The data indicate that the Pd-O-H phase is unstable compared to goethite, giving Support to previous observations that it is a transient phase in a transformation to native palladium.