well...im not sure of a certain specific page, but think of it this way;
oxygen is a strong oxidizing agent, with the second highest electronegativity of all of the elements. sulfur easily oxidizes to the dioxide, but also forms sulfites, sulfates, persulfates, thiosulfates and the like. copper and iron would only be cationic in these. so, im thinking they could form something like:
[math]FeS + Cu_2S + 4O2 --> FeCu_2(SO_4)_2[/math]
or it could form [math]FeCu_2(SO_3)_2[/math]