well, i liked this trip in BRD tonight; i probably have no real time to play this week before thursday, after we can go back if you still need.
There are a few spots outside BRD and MC for dark iron, in the searing gorge, maybe weird can mine there (on the hill of ogres on the east of the map). In BRD, there are mainly 2 locations for the mines: one is directly to the left after going in the instance (need to open the grid door which requires the key we have been running after for 2 hours), straight ahead after that door lies a huge cave where some mines can be spoted. The other location is near the entrance of MC, very far in the instance.
For the arcan cristals, there are found in the rich thorium mines (i believe the little ones cant). Same as for dark iron, i cant help you, required lvl is too high (need mining 275 for rich mines) But the droprate is pretty low, so i advice you to directly buy the 3 bars at the AH.
Hope this have been some help.
田畕畾畕田 - Mage Herborist/Miner/Grinder