Why is the extraction of copper from pyrites more difficult than that from its oxide ore through reduction?

Hello Student
The Standard free energy of formation of Cu₂S is greater than those of CS₂ & H₂S .Hence , niether carbon nor hydrogen can reduce Cu₂S to Cu metal.
On the other hand , standard free energy of formation of Cu2O is much lower than that of CO2 & hence , carbon can easily reduce Cu2O to Cu.
Cu2O+C (s) → Cu(s) +CO(g)