FeIIS2-I + 2 O20 Fe0 + 2 SIVO2-II

This is an oxidation-reduction (redox) reaction:

2 S-I - 10 e- 2 SIV (oxidation)

FeII + 2 e- Fe0 (reduction)

4 O0 + 8 e- 4 O-II (reduction)

Change the oxidation states