The third bonus of Miner's credo says "Ore mined smelts faster". But that is not the case basing on my experience. I have full miner's credo and tried to smelt ore which I extracted after getting the credo. The smelting time still was "12 coals" or 55 minutes. I tried to smelt both types of ore simultaneously in one smelter - mined before and after credo. They had exactly the same smelting time - 12 coals, which have always been the case before credos were implemented.
So my question is if I missing something or the credo bonus doesn't work?