This trial mine is situated on the western bank of Nant cwm-marydd, north of Brechfa village and is thought to date from the 1880's. The adit entrance is a few meters up from the stream via a trench. The first section is filled with water with a fall a few meters in. The fall seems to have exposed a seam of quartz. There are two turns beyond the fall. The last section seems to be in line with the seam exposed in the fall. There is no obvious access to the site.