Halse [1887: 110] reports that he was told by Joshua Lancaster that this outcrop could not profitably be worked because of the low grade ore (only 19% manganese) and the 6½ mile distance to the station. However, he was unable to find the outcrop himself because, he says, of “a heavy mist”.
Halse’s map shows a manganese outcrop to the south of the west end of Llyn Cwm Bychan (somewhere in the vicinity of SH637308) and Down [1980: 27] gives this as the location for Cwm Bychan mine. There is no mention of manganese mining remains at this location in [RCAHMW CARN] and no manganese outcrop is shown at this location by Allen & Jackson [1985b: 80]. Allen & Jackson [1985a: 57] show the location to be in the Rhinog Formation.
Down [1980: 36] suggests that the mine could be one of the Cwm Mawr group (Fridd Tyddyn Du, Cwm Mawr No. 1 or Cwm Mawr No. 2). Of the locations mentioned, only Fridd Tyddyn Du is anything like the distance from the station mentioned by Halse above, being approximately 6 miles from Llanbedr station. The other locations are all approximately 5 miles from the station.