Small underground working.**

Small ruined buildings, plus a small dwelling some distance away that may have been connected with the workings. The principal surviving feature is a substantial house incorporating workshops, with a smithy in a rear lean-to. The underground workings lie on two apparently separate levels. Above and behind the main site is an adit that appears to have been only a trial. Sections of the cart track leading from the quarry remain traceable.

Compact, isolated underground working centred on a single multi-purpose building used as a barrack and workshop. Finished slate was carried out to Croesor village for transport.