Meirionydd Manganese Mines

Introduction
British manganese reserves are very limited. At times during the last century, particularly the second World War, all of Britain's manganese came from North Wales. Small mines were worked in the Rhiniogs and on the Lleyn Peninsula as well as some outlying areas.

The ore was excavated by a combination of open cast and underground workings - the underground sites being mainly to the south.

Geology
The ore occurs in Cambrian Age rocks. Deposits develop at the base of the manganese shales which are 12 to 18" thick beds outcropping all around the Harlech Dome. Originally the oxidised surface layer was excavated from surface. Then adits were dug to reach unoxidised layers.

Harlech
Grid Reference: SH 595 322

Total Output 3500 tonnes. Two adits were driven into cliff face near A496 road.

Lletty Walter or Coed
Grid Reference: SH 605 280

Total Output 2000 tonnes. Opposite bank of river to Artro Mine. Upper and lower adits connected by incline.

Cilcychwyn
Grid Reference: SH 630 266

Total Output 1400 tonnes. Substantial underground workings with some opencast.

Cwm Mawr Mines
Grid Reference: SH 634 322

Total Output 7500 tonnes. Mainly opencast. To the north are a number of trial adits.

Crafnant
Grid Reference: SH 621 291

Total Output 30 tonnes. Short length of bed mined underground and on surface.

Cwm yr Afon
Grid Reference: SH 640 292

Total Output 500 tonnes. Mainly opencast with a couple of short adits.

Hendre
Grid Reference: SH 614 254

Total Output 3000 tonnes. Several large adits with collapsed levels above.

Moelfre
Grid Reference: SH 629 255

Total Output 5000 tonnes. Manganese mined along 1/2 miles of manganese bed with 4 levels. Also trial gold level.

Rhiniog
Grid Reference: SH 654 267

Total Output 2700 tonnes. A series of small adits leading uphill.

Cell Fechan
Grid Reference: SH 613 166

Total Output 900 tonnes. Substantial underground workings near St. John's Church.

Hafotty & Egryn
Grid Reference: SH 618 190

Total Output 12,000 tonnes. Hafotty was largest manganese mine in Meirioneth. Hafotty adjacent to Egryn. Egryn re-opened during WW1. Manganese mined using adits and shafts.

Cwm Mynach
Grid Reference: SH 681 214

Total Output 1600 tonnes. Extensive and dangerous underground workings in forest. Also levels and opencast above trees.

Votty
Grid Reference: SH 679 213

Stoped out from adits. Also opencast workings.

New Diffwys
Grid Reference: SH 667 225

Underground workings inaccessible, but visible via hole in opencast wall.