'Geology Manganese mineralisation occurs associated with minor N?S vertical faults. The host rock is yellowish tuff of the Llyn Conwy formation. [Lynas 1973: 497], In 1886 there was some interest in this mine. J Roberts of Bryn Crafnant, Trefriw wrote to E Watkins (the Rhiwlas estate manager) in June saying that a friend of his was anxious to get a manganese mine and Nant yr Helfa would suit him. He wrote again in July asking if the mine would become open soon as he felt he could do something with it [GAS DAO: Z/DDD/2/579, 601].
At the end of 1906 a lease was drawn up for R J Lloyd Price and William Owen for the mining rights at Nant yr Helfa (together with Caefadog, Cwm Cottage and Rhydyfen) for one year (with provision for converting to 20 years in a year's time) for a consideration of £20 p.a. with a royalty of 1s/ton of manganese [GAS DAO: Z/DDD/3/22, 25]. (The lease also included the right to work graphite with a royalty of 1/10th of the value of graphite produced.)' Linton, DJ, 2005 Merioneth Manganese, Bryn Ffolt. 'NANT YR HELFA MINE MANGANESE LLANYCIL MERIONETH SH832401
References:
Linton, D J, Merioneth Manganese, 2005 Nant yr Helfa
National Library of Wales ? Henry Robertson of Pale papers 4/65?141 1873?1886: Evan Jones of Bala report on mines and quarries that would become tributaries of the Bala & Ffestiniog Railway : Ordnance Survey six-inch map of Merioneth (2nd Edition) ? Sheet No. XIII SE
Notes: no company registered with this name ' Wilkinson, J, 2004 The Mines and Quarries of North Wales. Gwynedd HER. OAN Site Visit 2008. The site consists of a group of trial workings on the hillside above the main road and straddling Nant yr Helfa. On the south end of the site is a working/crushing floor (NPRN 514735) which is accessed by a trackway (NPRN 514736). There is no surviving evidence for a structure housing mineral processing on the floor but there is a tipping ramp on the western end of the trackway, adjacent to a wheelpit (NPRN 514734), which is in turn fed from Nant yr Helfa by a millrace heading downslope from the north (NPRN 514733). There is one surviving open adit on the hillside (NPRN 514705) and many areas of trial workings, and in the south more intensive extraction (NPRN 514704, 514706, 514707, 514728, 514729 and 514740). P.J.Schofield, OANorth, 7th January 2009.