Abstract
Bryn-y-groes Lode.—About 500 yards east of the Clogau lode, there is a parallel lode which has been worked for copper. Striking 50° east of north, its outcrop may be traced for about 1½ miles; its width is very variable. Chalcopyrite and pyrites and a little gold are present in the quartz. The lode is confined to the Vigra Beds, and running with the beds, it is associated throughout its length with greenstone sills.