Abstract: The results of experimental modeling of the arsenic transition from natural arsenides to mobile oxidized species in the near-surface environment are discussed. The experiment has been carried out with the samples collected from the dump of the Schlema-Alberoda deposit. Arsenides (safflorite, löllingite, nickeline, rammelsbergite) have been dissolved in acidic and near-neutral oxidative media for a month. As a result, the new data on arsenic leaching capability in order to form new phases (annabergite, scorodite, and iron hydroxides) have been obtained.