4 CuIIFeIIS2-II + 9 O20 2 Cu2IS-II + 2 Fe2IIIO3-II + 6 SIVO2-II

This is an oxidation-reduction (redox) reaction:

4 CuII + 4 e- 4 CuI (reduction)

6 S-II - 36 e- 6 SIV (oxidation)

4 FeII - 4 e- 4 FeIII (oxidation)

18 O0 + 36 e- 18 O-II (reduction)

Change the oxidation states