To the north of the fortress Cromm Bráighe lay the Gleann Ruadh, where the Mitheithel had cut a small valley with a few strips of good ground and some readily available copper deposits. These veins of metal once attracted Eriadoran miners and númenorean explorers but most of the copper nodes ran out long ago.
The Mine was Partially collapsed by the locals, as Trolls tended to lair in such places. A secret passage from the mine led to the Ureithel, the cavern at the base of the rock.This was only one of several holes in the ground in this area.There was a Secret Mine Entrance once used by Eldacar in T.A. 164. While it was only one of many mine openings in this area, it could be located by a persistant searcher who knews the tale of Mongán Finn and Miffli—and the defences at the Ureithel had been set up with this in mind.