Reguardless of str, mining still feel level based, unlike all the other perfessions, the actual how well you mine is dependent on how many attacks per round you can make. 2nd level characters could get very high in any other skill in a short amount time if they was working on it, but mining at one attack per round with a pick could take 15-30 min without power attack to get a full vein
once you have 2-3 attacks per round, could take five miniutes to do this work