I would like to share my favorite mining place for three ores.
I go to the Burning Steppess for thorium, mithril, and dark iron ore. In one trip around the perimeter you can collect alot of mith and thorium and dark iron coming mostly in the southwest corner. Also near the orge mound and inside their caves you can get alot more. The orges mountain can almost be half of what you can get around the perimeter so i suggest taking a trip there first then going around the perimeter.
Also there are not to many mobs you have to worry about just a few stragglers on the way.