Characterization of secondary products in arsenopyrite-bearing mine wastes: influence of cementation on arsenic attenuation.

•Characterization of cemented phases/layers in an arsenopyrite-bearing mine waste dump.•Hardpan comprised cemented fragments of (altered) sulfides and other gangue minerals.•Amorphous ferric arsenates (AFA) were the binding agent in cemented phases/layers.•As mobility from hardpan was not decreased as compared to that of not cemented phases.•The low pH conditions allowed the AFA occurrence and the hardpan temporary stability.