CPAT Regional Historic Environment Record
The following information is from the on-line database Archwilio

Craig-y-Mwyn Mine

Primary Reference Number (PRN) : 8438
Trust : Clwyd Powys
Site Type : Lead mine
Period : Multiperiod
Community : Llanrhaeadr-ym-mochnant
NGR : SJ07422852
Legal Protection : scheduled ancient monument

Description :
Lead (Roman ?/17th century/18th/1845-1880)

Ordovician Llangynog formation shales, slates and tuffs. There are 2 ENE-WSW veins & 2 E-W veins. Mineralisation includes galena and sphalerite in a dominantly calcite, quartz and barytes gangue.

There are extensive hushing earthworks on top of the hill SJ07472848 with 2 semi-circular dams close to the rim of the main opencast and numerous leats contouring the hillside from a bog source and exiting into the quarry like opencast. 'Miners Pools' are indicated on a plan of 1855 and are almost certainly other hushing dams or water collection ponds. The latter are now lost in an extremely wet boggy area at SJ07562810 and only one was recorded on the brief site visit. Aerial photographs show three small rectangular pools with associated leats which appear to exit into the quarry opencast at a more easterly location.

There are a number of linear trial trenches on top of the hill north-west of the opencast at SJ07202870. There are eight visible levels, a shaft to the south of the opencast on top of the hill at SJ07352830, a deep adit to the east below the opencast, some open stoping within the opencast itself and numerous shallow trials around the rim of the opencast. Below the opencast the hushing activity has formed a very large fan of debris which extends all the way to the dressing floors.

There is a tramway running from the No.1 level to the bottom of the opencast. A steep incline runs downhill from just east of the No.4 level to the dressing floors SJ07632860. On the 1885 plan of the mine a trough like ore chute was in use in the same position as the later incline. The incline has been cut through by a recent farm track revealing a section of its construction.

A leat at SJ07712885 contours the base of the hillside to the north of the dressing floors and runs south into a storage reservoir for powering processing machinery at SJ07762879. The leat was fed by the Afon Disgynfa and Nant Y Gaseg. There are at least 4 leats on top of the hill feeding the hushing dams. The leats originate from bog sources at SJ07402817 & SJ07372857.

A 30x4 ft diameter waterwheel drove the crushers.

An incline winding house is situated at the head of the incline SJ07602861 with remains of the iron fixing bolts for the winding gear in situ. Part of a four foot diameter cast iron wheel, probably belonging to the winding wheel, can be seen alongside the incline trackway.

A stone breaker and crusher were situated close to the reservoir at the base of the incline at SJ07732878. The crusher house wheelpit and crusher housing survive. Stone platforms and walls to the south of the crusher probably represent the bases of a picking table and jigger bases. Round buddles and ore bins were also present but are not now identifiable on the ground.

Other features
There is a magazine above the dressing floor reservoir at SJ07752880. There is a possible small mine office/smithy at the entrance to the smithy level. Workshops are situated to the SE of the dressing floors with stables and miners' cottages further to the east.

At the western extreme of the opencast there is a rectangular building divided into a number of rooms which may relate to the eighteenth century activity at the mine. The building survives at foundation level only at SJ07432853.

Another rectangular building with southern and eastern square room extensions can be seen 100 yards to the south of the opencast alongside the present trackway at SJ07452834. This structure may have agricultural origins rather than an association with the mine.
(CPAT Metal Mines Survey)

1. Location

1.1 The main mine workings appear as a huge open-cast on the eastern slopes of Y Clogydd, clearly visible to the west of the road from Llanrhaeadr-ym-Mochnant to Pistyll Rhaeadr. The dressing floors lie on the valley floor c.5km north-west of the village, while the hushing evidence is located on the slopes of Y Clogydd and Moel Mawr on the southern edge of the Berwyn Mountains.

2. Geology

2.1 Solid geology - Ordovician Llangynog formation shales, slates and tuffs. Four recognised mineral veins include galena and sphalerite with calcite, quartz and barytes gangue minerals.

3. The Survey

3.1 The survey is principally restricted to the recording of the hushing system and other mining features on the hilltop above the open-cast (see Plate 1), and excludes the dressing floor areas, the incline and the lower workings. The survey has been divided into three sections to describe separately the hushings, the trials, levels and other workings and finally non-mining features.

3.2 The Hushing System

3.2.1 The evidence for hushing consists of a series of leats drawn from various sources in a boggy valley c.300m W of the open-cast. The leats feed a system of reservoirs of varying size, which in turn supply a complex of hushing channels along the edges of the open-cast.

3.2.2 A mine plan of 1855 (Williams 1985, 76) identifies three 'miners' pools' to the west of the main mine workings. The survey identified two pools located within the shallow valley mentioned above, both completely silted.

3.2.3 The upper pool (PRN 18386) is defined by a bank c.0.6m high damming the valley to create a pool c.510m sq in area. A leat (PRN 18387) flows from the SE corner contouring around the hillside E to feed the main hushing system.

3.2.4 The lower pool (PRN 18388) has an area of c.265m sq similarly defined by a bank 0.7m high. From the SE corner, a leat (PRN 18389) follows the contours E towards Level No.1 (PRN 18369). Further downslope another leat (PRN 18390), with its source in a boggy area to the west, leads in a similar direction. It would seem likely that they fed hushing channels which have been obliterated by later workings.

3.2.5 At the point where the lower leat (PRN 18390) crosses the stream below the lower pool, a hushing channel (PRN 18392) is directed from the stream to the SE. The channel increases in size as it progresses downslope to a maximum of c.5.9m wide and 0.9m deep. It is possible that the leat masks an earlier dam across the stream to feed the hushing channel.

3.2.6 There was no clear evidence for the third 'miners pool', although above the upper pool the stream had been dammed to direct water into a higher leat (PRN 18385) which is also fed by a further leat (PRN 18384), also leading from the stream. This leat contours E for c.295m with evidence of two former courses at its eastern end. The upper of these turns steeply downslope into a probable early hushing channel. It would seem likely that this leat fed the substantial hushing channel (4.5m wide and 1.35m deep) running SW-NE into the open-cast and subsequently blocked by later workings.

3.2.7 The most substantial hushing channels appear to have been fed by three large reservoirs. The northernmost reservoir (PRN 18357, Bick's Pond A) is defined by a large bank c.1.3m high and 3.8m wide enclosing an area of 365m sq with the site of a sluice along the SE side. This reservoir has been partly infilled by the construction of the modern farm track. There is no clear evidence of a leat sytem feeding the reservoir, although a short section of leat appears to feed in from the SW and there is a possible inlet channel to the NW.

3.2.8 The second reservoir (PRN 18358) has been largely destroyed by the modern farm track, with earthwork banks surviving only on the SE and NE sides. It is possible that leat PRN 18385 had been used to feed the reservoir. A further leat (PRN 18374) not necessarily associated with the reservoir, curiously flows from N to S away from the open-cast, apparently feeding into leat PRN 18387.

3.2.9 The third reservoir (PRN 18359, Bick's Pond B) may originally have been considerably larger than it now appears, with possible infilling by the spoil tips SE of a building (PRN 18360). The reservoir is clearly defined by an earthwork bank along the S and E sides, measuring 1.3m high and 4m wide at its greatest extent. Faint traces of a leat are visible feeding into the SW corner and a leat and hushing channel emanate from the NE corner.

3.2.10 Hushing along the S edge of the open-cast is also fed from two other sources. Leat PRN 18373 flows SE of the reservoir PRN 18359 with a small rectangular reservoir (c.8 x 3.5m) along its length (PRN 18368). Further E lies another rectangular reservoir (PRN 18364) measuring 10 x 5m. A leat flows from the NE corner, but there is no evidence of a feeder leat.

3.2.11 A separate system of leats and reservoirs fed hushing S of the open-cast along the eastern moorland slopes. The open-cast below, and the spoil fan at its base, provide further evidence for hushing. The only leat (PRN 18372) feeding into this area can be traced N of enclosure PRN 18379 with no evidence of its source. A sub-rectangular reservoir (PRN 18367) c.7.5m x 6.7m along the course of the leat would have provided a reservoir and controlled the flow of water.

3.2.12 Two small irregular reservoirs (PRN 18365-6) appear to be fed by the above leat, with an outflow to the SE.

3.3 Other Mining Features

3.3.1 Only one shaft (PRN 18375) is located on the high ground above the open-cast. It is presumed that this shaft was sunk by Henning, the mining agent for Powys Estates, in 1747 (Williams 1985, 89). A possible platform for winding gear is evident on the N side of the shaft. There is no evidence to suggest that ore was raised or dressed at this location. Williams (1985, 89) suggests that the shaft connects to No. 1 Level (PRN 18369).

3.3.2 The substantial level (PRN 18369) on the eastern slopes of the plateau, with extensive spoil tips below, is documented as No. 1 Level on the Powys Estates' mine plan of 1855 (Williams 1985, 76). The spoil tips suggest that the ore was sorted before being lowered to the tramway (PRN 18377) below. Above the level are two areas of collapse.

3.3.3 Substantial trials consisting of at least four small shafts and a collapsed level (PRN 18370) are located SW of No. 1 Level. The collapsed level appears on the OS 1889 map. Further shallow trials (PRN 18371) exist to the SE and along the edge of the opencast.

3.3.4 A separate area of trials (PRN 18376) is located to the west of the main opencast.

3.3.5 The remains of a rectangular stone building (PRN 18360) lie adjacent to and possibly within the original extent of the large pond PRN 18359. The dry stone walls are 0.5m thick and generally only survive to basal layers. The building measures c.12m x 4m overall, with the addition of an outbuilding against the N wall. Internally, the collapse suggests it is divided into two rooms. It is assumed that this is the house and smithy recorded in 1751 as a two-roomed building (Powys MS 21712, NLW).

3.3.6 A small roughly square enclosure (PRN 18362) c.10m across lies SE of the reservoir PRN 18359, defined by low earthwork banks c.0.35m high and 1.3m wide, with an entrance on the SW side. It is uncertain whether this feature is related to the mining activity.

3.3.7 A large sub-rectangular enclosure (PRN 18363) measuring c.31.8m x 19.3m is situated between the two leats PRNs 18372 and 18373. The earthwork banks survive best on the N and W sides, 0.4m high and 0.8m wide. A track leads to the entrance on the S side, adjacent to a possible building platform within the enclosure, measuring c.12 x 6.5m.

3.3.8 A possible building platform and enclosure (PRN 18378) lie 40m east of the shaft (PRN 18375). The platform measures c.21.4m x 6.8m with a sub-division 6.4m from the southern end. Low dry-stone walls define the platform surviving to a height of c.0.5m. The general lack of tumbled stone would suggest that the walls were originally only slightly higher, unless substantial robbing has occurred. The E wall lies on top of the field boundary (PRN 18381).

3.3.9 A palimpsest of tracks (PRN 18393) lead uphill towards the platform, presumably forming the original access to the site. The original track (PRN 18391) from Tan-y-graig and the dressing floor area leads upslope from the SE, partly obscured by the modern farm track.

3.3.10 To the SW, a track (PRN 18382) runs south and presumably leads to the early 18th century Cubil Smelting House (PRN 18319) located by Williams (1985, 69) in Cwm Glanhafon on the W slopes of Craig Rhiwarth at SJ063268.

3.3.11 At the northern extent of the survey a series of low platforms (PRN 18356) may be associated with the mining activity.

3.4 Other features

3.4.1 A series of old field boundaries are evidence of a former, presumably post-medieval field system. Some of the boundaries appear to be contemporary with certain mining features, while others appear to post-date them.

3.4.2 The main field boundary (PRN 18381) runs roughly N-S, pre-dating the possible building platform and enclosure PRN 18378. From the SE corner of the platform another boundary bank (PRN 18380) runs downslope to the east, apparently post-dating leats PRN 18389 and 18390. In the NE angle between the two boundaries is a small enclosure or sheepfold (PRN 18379) measuring c.10.2 x 7m.

3.4.3 Further S, a boundary (PRN 18382) diverges to the SW, following the track to the Cubil Smelter at SJ063268 and track PRN 18394 runs off it. It is evident that of the palimpsest of tracks S of the platform, the latest follows the boundary, while the other are overlain by it.

3.4.4 A sheepfold (PRN 18530) of dry stone wall construction was recorded on the 1889 OS map.

4. Conclusions

4.1 The hushing remains form one of only two such sites in Powys, and are potentially of an early date. The system of leats and reservoirs is one of the most extensive in Wales, and as such is worthy of statutary protection.
(CPAT Metal Mines Survey - ground survey)

SCHEDULED ON 20/05/98. Of national importance as an exceptional complex of early mining remains, including rare evidence of hushing and primitive opencast.

Excavation and sampling by Simon Timberlake in 2002 (PRN 49995).

Sources :
Bick, D E , 1978 , The Old Metal Mines of Mid Wales 5
Foster-Smith, J R , 1978 , The Mines of Montgomeryshire and Radnorshire
Bick, D E , 1990 , The Old Metal Mines Of Mid-Wales
Williams, R A , 1985 , The Old Mines of the Llangynog District
Clwyd Powys Archaeological Trust , 1983 , Site visit record - PRN8438
Cadw , 1998 , Cadw Field Monument Wardens Report - Mg249(POW)
Ordnance Survey , 1889 , OS map
Cadw , 1998 , Scheduling map - Mg249(POW)
Timberlake, S , 2002 , title unknown - Dylife Mine etc
Jones, N W and Frost, P , 1996 , Powys Metal Mines Ground Survey 1994

Events :
319259 : Craig-y-Mwyn Mine, field visit 1997 (year : 1997)
49995 : Craig-y-Mwyn Mine, excavation 2002 (year : 2002)
337071 : Craig-y-Mwyn Mine, field visit 1983 (year : 1983)
123076 : Powys Metal Mines, topographical survey 1994 (year : 1994)

Related PRNs : 8438

Archaeological data, from the Historic Environment Record, supplied by The Clwyd-Powys Archaeological Trust in partnership with Local Authorities, Cadw and the partners of ENDEX CPAT, 2013 (and in part Crown, 2013). It is intended to be used for private research only and is not for use as part of commercial projects. If you wish to use this information for publication in printed or multimedia form or to compile resources for commercial use, prior permission must be obtained in writing. Use of this information is subject to the terms and conditions of access to HER data published on CPAT's website. Please contact the HER if you have any further questions regarding this information. Please quote the Primary Reference Numbers (PRNs) in any correspondence.

July 31, 2014, 3:20 am - File produced for Archwilio from CPAT's Regional HER.
Clwyd Powys Archaeological Trust, Curatorial Section, 41 Broad Street, Welshpool, Powys SY21 7RR.
tel (01938) 553670, fax (01938) 552179, website

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