I have taken about 20 stacks of tin and 2 stacks of silver (and countless stacks of copper) out of the Coast Quary in Westfall over the last week or so (maybe 20 hours played). At about level 20 the mobs are trivial but they do pop back rather quickly, so you will end up with a lot of green items and linen cloth...so there are some AH fodder as well.
All told the coast quary is basically a money farm for miners when the deadmines are still too high.