Snowdonia Mines

Introduction
The Snowdonia copper mines operated from mid 19th C to early 20th C. Much of following information comes from personal experience and browsing through The Old Copper Mines of Snowdonia by David Bick. As with the lead of the Conwy Valley, the lodes are mainly confined to normal faults in Ordovician rocks of Llandeilo and Bala age. Copper ore - mainly copper pyrites often occurs together with galena. The mines were on a much smaller scale than those of Anglesey and usually worked at a loss. In terms of ore output for the period 1804 to 1931, the most prolific mines were Drwsycoed 13,000 tonnes, Simdde Dylluan 8,000 tonnes, Llanberis 7,500 tonnes, Snowdon 3,000 tonnes, Lliwedd 2,000 tonnes and Sygun 1500 tonnes. This gives an idea of the extent of the workings.

Minor amounts of iron ore has been exploited in N Wales. Bedded oolitic or pisolitic iron ore of Cambrian and Ordovician age cropping out on Anglesey and various parts of Gwynedd. Not hydrothermal veins but iron precipitated in the sea within the Nant Ffrancon formation during sedimentary deposition. Worked during later half of 19thC and early part of 20C. Maximum output of 80,000 tonnes in 1857. Row of large stoped workings up the mountain just down the road from Betws Garmon - Ystrad Mine. Dipping northwards at 70deg. Other small workings at Llandegai, Aber and Nant Ffrancon Pass.

Porthmadog and Llanfrothen Area
Apart from the isolated mine at Bron y Gadair, the workings are concentrated near the Ffestiniog Railway near Penrhyndeudraeth. Apart from the workings listed, there are a number of smaller trials and surface mineralisation features. Bwlch y Plwm although associated geographically is discussed in the Lead & Zinc section.

Bron y Gadair (copper)
Grid Reference: SH 523 393

Between Criccieth and Porthmadog. Small adit and shaft. The shaft is reputed to be hundreds of feet in depth.

Pant-y-wrach (copper)
Grid Reference: SH 617 402

In woodland on hillside near Llanfrothen to Penrhyndeudraeth road. There are two sets of workings exploiting 2 veins. The western workings are exploited by a series of surface stopes with extensive workings underneath. There are a number of routes down to the intermediate shallow adit level (shallow adit blocked). One route entered via a short adit leads to a bolted route. A 100’ shaft split in two descends to the deep adit level. Deep adit is blocked by collapse after about 150m. Deep adit entrance can also be entered from near the eastern workings and followed for a short distance to the collapse. The eastern workings is accessed via an adit leading to a stope. Currently blocked passage probably leads to the large stopes which can be entered from above via a surface shaft.

Catherine and Jane Consols (copper)
Grid Reference: SH 633 411

Workings in forest above Ffestiniog railway near Penrhyndeudraeth. A steeply inclined square shaft approx. 120' deep intercepts three levels, bottom blocked and upper unsafe. Middle level with nice flatrods emerges to daylight after constriction. Surface location of deep adit unknown. The extremity of the Bwlch y Plwm adit is not far from the property boundary and there were plans to extend it to drain Catherine and Jane Consols. This is an interesting area, exploration being made difficult by the forestry.

Cae Fali (copper)
Grid Reference: SH 631 405

Lower down the valley from Catherine and Jane Consols is an un-located adit draining workings at Cae Fali.

Rhyd Mine (copper)
Grid Reference: SH 637 416

Further to the east near the village of Rhyd is another as yet unidentified working marked by spoil and building remains. An adit from the top of spoil heap extends some distance with vertical stopes underneath

Bwlch-y-plwm (lead)
Grid Reference: SH 626 413

About a mile to the east of Pant-y-wrach. Workings on 5 levels. A long adit near a bend on the minor road leads to stopes and passages. A 100' shaft from the upper level enters the stope. Higher up the hillside above farmhouse are other stopes and shafts. Other levels are present in this area. Shafts have been bolted, ropes (some in bad condition) installed on a traverse and a small bridge across a stope.

Moel Hebog (copper)
Grid Reference: SH 558 472

Altitude 1700' between Moel Hebog and Moel yr Ogof in Cwm Pennant. Marked on OS map. Also known as Cwm Llefrith. Large entranced adit and cavernous stopes. A shaft highert up the hillside also communicates. There are a number of smaller trial workings.

Dinas Great Copper
Grid Reference: SH 531 484

Trial levels on hillside. Worked with Moel Hebog.

Cwm Cipwrth (copper)
Grid Reference: SH 526 478

Well known for it's restored waterwheel adjacent to stream. Various adits and stopes.

Gilfach (copper)
Grid Reference: SH 531 477

Near first gate on the road. The workings are on a wooded hillside near Cwm Cipwrth. A long 5’ high Deep Adit leads to lodes. An upper adit leads to a 50m shaft to deep adit. Higher up the hillside again is a fenced up surface shaft, presumably dropping into the middle level. There are the remains of a mill near the Deep Adit.

Blaen y Pennant or Blaen Cwm Dwyfor (copper)
Grid Reference: SH 541 505

At head of Cwm Pennant. There are various old shafts. This was the only copper mine in Snowdonia with a direct rail link to a port which it achieved with a branch to the Prince of Wales slate quarry line.

Prince of Wales (slate)
Grid Reference: SH 549 498

Open quarry with some underground chambering on three levels.

Drwsycoed (copper)
Grid Reference: SH 545 534

Many enterable workings. Lefel Las to south of road is about 800’ of tunnels. Stope on hillside above Lefel Las. Nearby is a vertical shaft. Access is sensitive and should not be attempted without consulting landowner.

Simdde Dylluan or Talysarn (copper)
Grid Reference: SH 543 533

Four lodes. Shafts blocked but many workings still open. The main open working has a stope with false floor leading to a ladder downwards. Used to be deepest workings in Snowdonia.

Benallt, Nantlle Valley (copper)
Grid Reference: SH 536 535

A number of adits and trial levels across valley from Simdde Dylluan. The 600’ long deep adit reaches stope workings which can be climbed via two ladder shaft to an upper level whose adit is blocked by old fences. There is a second series of working extending up the hillside. The bottom adit is open, second blocked and third has deep shaft just inside entrance.

Gwernor (copper)
Grid Reference: SH 502 525

Number of fenced off shafts and adits up hillside behind row of cottages. Cottage has ore tub and working waterwheel in garden.

Ffridd Isaf (copper)
Grid Reference: SH 570 529

Near Rhyd Ddu. Workings near old railway. Two 20’ deep crosscuts linked by 100’ level.

Brynfelin (copper)
Grid Reference: SH 589 472

Pre 19th C mine. A blocked long adit emerged near old mill on river bank. At the base of a wooded hillside are a series of inclined open stopes about 80’ deep joining with the Deep Adit. There is also a stone lined shaft. Some stopes are blind, others tricky to descend.

Lefel Goch (copper)
Grid Reference: SH 593 466

Aberglaslyn Pass. Marked as a spring on the 1:25,000 map. Now blocked. Was long, ancient adit. Red water drains through wall near road. Some ore cuttings on rough hillside above.

Aberglaslyn (copper)
Grid Reference: SH 594 462

In woods behind house near Aberglaslyn bridge. On same vein as Nantmor mines. A deep adit behind the house and a series of workings to a large stope leading up the hillside. On opposite side of river bank near wooden bridge is adit at river level.

Cwmbychan or Nantmor (copper)
Grid Reference: SH 602 472

Famous for it's aerial ropeway. Various levels, stopes and trials. Main workings are two crosscuts to lodes both of which are stoped 80’ up to surface. Further up the valley is a 300’ long trial adit.

Cwm Croesor (copper)
Grid Reference: SH 638 453

Un-named mines. Prominent entrances with spoil visible across valley from the Croesor incline, probably copper. The OS map shows other workings on this side of y Cnicht.

Llwyndu or Cribddu (copper)
Grid Reference: SH 606 483

On other side of hill from Sygun. Short adit to stope. Inclined stope up leads upwards to surface holes. Bottom of stope flooded. Just to north near old dressing floor is a covered flooded, open shaft connecting with deep levels. It is uncertain whether the levels are accessible.

Sygun (copper)
Grid Reference: SH 606 488

Well known, extensive show mine between Llyn Dinas and Beddgelert. Entry is through Deep Adit and exit through Victoria Level. Other levels are scattered across hillside.

Perthi (manganese)
Grid Reference: SH 592 486

Opencuts and levels close to footpath behind Beddgelert, Currently un-located.

Also rumored mine on hill between Prenteg and Cwm Ystradllyn, presumably that marked as Old Level near Llyn Du on the OS Map.

Hafod y Llan (copper)
Grid Reference: SH 623 523

Cwm Llan above Nant Gwynant. Scattered workings shown on OS map. High on hillside to east of mill near river. Numerous opencut workings and levels up side of mountain. Remains of buildings.

Braich yr Oen (copper)
Grid Reference: SH 614 516

Cwm Llan above Nant Gwynant. 75 yard level near buildings enters large open stope.

Hafod y Porth (copper)
Grid Reference: SH 611 506

To north of Llyn Dinas. Adit, trial shafts and levels spread over wide area.

Lliwedd (copper)
Grid Reference: SH 634 531

Adits, trial shafts and large open workings situated at an altitude of abut 1500’.

Panku (copper)
Near top end of Llyn Gwynant. Unlocated..

Snowdon or Britannia (copper)
Grid Reference: SH 616 547

2000’ high above Llyn Glaslyn. Extensive workings on several levels with interconnecting stopes. Some of the upper levels are now blocked, but it is still possible to pass from the top levels through to the bottom. There is a lot of rather shaky looking woodwork in evidence.

Clogwyn Coch (copper)
Grid Reference: SH 603 556

Clogwyn Du’r Arddu. Entrance visible underneath spoil from higher workings is run in about 20’ from daylight. Higher up hillside are precariously situated surface workings. Unconfirmed rumours, probably anecdotal that it was linked underground to Britannia.

Glynrhonwy (slate)
Grid Reference: SH 570 610

Series of pit workings. Tunnels connected the two pits of Glynrhonwy Upper, Glynrhonwy Lower and the Llanberis Railway. Used by the Air Ministry for storage following second world war.

Llanberis (copper)
Grid Reference: SH 597 587

At head of Llyn Peris near Nant Peris Marked by prominent spoil. Consisted of Lower Works, Yew Tree Works, Smithy Works and Bridge Works, the contemporary identification of which is confusing. A gated, wet deep adit near road. Higher up an adit leads to a high stope. Near stope is shaft in floor which probably enter blocked middle level and bottom deep adit. Further up hillside workings stoped to surface. There is also a blocked North Adit near lake. The deep adit extended several 100 feet and had very high stopes and timber floor.

Gwaith (copper)
Grid Reference: SH 632 633

Workings grassed over apart from 100’ adit up hillside.

Ceunant (copper)
Grid Reference: SH 633 645

Near bend in river. Mined for arsenic. Adit and number of blocked surface shafts follow lode. Also interconnecting flues made of stone flags for sublimation of arsenic.

Cwm Ceunant (copper)
Grid Reference: SH 626 637

Prominent dumps on west side of Nant Ffrancon. Number of levels 60’ apart vertically. Bottom adit is blocked. Middle adit has dangerous traverse above 80’ shaft to base of another shaft. Top adit soon leads to head of shaft with old chain and timber remains.