Yep, you found copper rocks -- there are more copper rocks in the entry underground zones than iron rocks. The mining rocks respawn as soon as you see them disappear, but they do not respawn in the same spot, you have to search for them. Note that the monsters in the entry underground zone are similar throughout the zone. As long as you do not go into the next zone, the monsters won't change much. I'm guessing you just didn't venture throughout the zone enough -- it's a fairly large area
Looked around first area, Before going to 2 nd entrance, did not see any other rocks to mine, try look around 2 nd entrance have yet see any stones. very limited amount stones looking, At point lack magic res for howler dmg or need find better gear. move further in then starting area sizable area there as is.