Cyfaned Fawr has been recorded as a lead and copper mine by Gwynedd Archaeological Trust. The adit was driven in 1842, but when operations ceased pre-1887, the mine was working as a slate works. On Ordnance Survey County Series maps dated 1889(Merionethshire XXXVI,15) the site is described as a disused slate works (NPRN 413821).
Remaining buildings and industrial works include shafts, masonry ore slides, a wheelpit, a roofless crusher house and settling pits.
Source: David Gwyn & Merfyn Williams (1996) `A Guide to the Industrial Archaeology of North West Wales?. Association for Industrial Archaeology
