CPAT Regional Historic Environment Record
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Nantiago Mine

Primary Reference Number (PRN) : 5944
Trust : Clwyd Powys
Community : Llangurig
Unitary authority : Powys
NGR : SN82608630
Site Type (preferred type first) : POST MEDIEVAL LEAD MINE

Summary :
The Nantiago workings extend for over half a kilometer along the Nant Iago stream. The earthwork and structural remains on the main mine site date from the mid-19th century to the end of production in 1913.

Surviving remains of the mine include an uncapped engine shaft with part of the pump rod in situ, foundations of the winding house or drum house, concrete structures, ironwork, winches with wheels and cables, wheelpits, reservoirs, quarries, dressing floors, spoil tips, ore bins, dressing plants, crusher house and culverts. There are also remains of some of the Pelton water wheels, wooden jiggers, wooden launders, settling pits, building platforms, a smithy, dams to divert water to feed the leats - one of which was at least 2 miles long and numerous tramways. A miners' barracks, a store shed, mine office, and magazine are present but are poorly preserved.

The surviving remains would appear to belong to two main periods of activity. Features clearly belonging to the earlier phase, dating c. 1846 to 1880s, relate mainly to the original dressing floors and consist of the ore-bins, crusher and wheelpit and adjacent platforms, together with winding and pumping equipment associated with the main shaft. The later phase consists of the substantial processing plant of 1900, together with its ancillary features. This structure is a rare survival of a late machine driven mill and is the best preserved within the Powys orefields and has the highest concentration of in situ machinery and other dressing floor features on a mining site in this area (CPAT Metal Mines Survey).


Description :
Lead (1846-1917)

Geology
Ordovician Upper Van mudstones and grits. The main vein has a ENE-WSW strike. The N-S cross vein has calcite with galena and sphalerite.

Workings
A shaft and deep adit plus two other levels are visible. There are numerous small trials on the surrounding slopes.

Transport
Numerous tramways for running the ore from the adits to the dressing floors are visible.

Power
Leats running off from Nant Iago supplied water to three waterwheels and 2 Pelton wheels used for pumping, drawing and processing. The pumping wheel reached a maximum size of 60ft diameter. One cast iron Pelton wheel is intact and in situ on the dressing floor. A small gas engine was also formerly present on the dressing floor. The line of the high pressure pipe to the Pelton wheels can be seen as a scar on the hillside above.

Processing
In 1900 a new three-storey processing mill was erected which was driven by 2 Pelton wheels and included a stone breaker, rolls, trommels, and six 4 compartement jigs. This replaced a dressing floor about which we have little information. The 1900s mill is partially intact on the ground floor with much processing machinery either in situ or scattered around. Much woodwork survives. A collapsed trommel screen is still in place together with a Pelton wheel and part of a belt driven drive shaft. A small feeder cone is also present. It is possible that other machinery lies buried within the main structure.

Other features
Miners' barracks SN82558631, a store shed, mine office, and magazine are present but are poorly preserved.

The cast-iron winding wheels from the shear legs and adjacent cage winder are present in the top of the shaft along with other debris. A cast-iron winding drum with gear wheel and rewound cable is partially buried in a spoil tip adjacent to the shaft SN82478638.

Comments
This site has two important features:

(1) The 1900 processing plant is the best preserved of its kind in the West Montgomeryshire orefield. It also has the highest concentration of in situ machinery and other dressing floor features on a mining site in this area.

(2) Other machinery parts related to the engine shaft winding gear survive in part. Again this is the most intact assemblage in West Montgomeryshire.
(CPAT Metal Mines Survey)

1. Location

1.1 The mine site is located E of Plynlimon, c.1.5km N of the Wye Valley Mines in the Nant Iago valley, a tributary of the River Wye.

2. Geology

2.1 Solid geology - Ordovician mudstones and shales of the Lower Van formation. Mineralisation on a main ENE-WSW vein includes galena and sphalerite.

3. The Survey

3.1 The survey revealed an area of mining activity not previously identified. Nantiago West (PRN 18588) appears to represent trials by the Nantiago Company in the valley of the River Wye at SN81508630. The main shaft and its stone built bob-pit (PRN 18549) are located at SN81508630. The shaft and bob-pit were powered by a waterwheel; the stone wheelpit (PRN 18547), measuring c.8.5 x 1.5 x 2m deep internally, is located at SN81258650. The wheel is fed by a leat (PRN 18548) which runs off the River Wye. The masonry walls of a mine office or stores (PRN 18550), c.4 x 5.7m externally, survive to c.1.5m high at SN81208645. The OS has recorded a second shaft at SN81508630, but this remained unlocated in the dense moorland. Also recorded further to the west is a level at SN80358580, which may also relate to Nantiago Mine.

3.2 Upstream of these workings, the river is dammed by a substantial stone-revetted earthwork dam (PRN 18551) c.11m high x 12m wide x 100m long. The water was diverted at this point to feed the main leat (PRN 18576) of the Nantiago Mine. In 1860, The Mining Journal (Vol.30) reported the completion of a leat two miles long, which was to power the pumping, winding and crushing machinery.

3.3 The earthwork and structural remains on the main mine site date from the mid-19th century to the end of production in 1913. A modern farm track runs along the eastern perimeter of the dressing floor areas and forms the E boundary of the survey.

3.4 Engine Shaft (PRN 18578), located at the NW corner of the site was sunk to 30 fathoms below the adit level (PRN 18566), and remains uncapped with part of the pump rod system in situ. The foundations of the winding house or drum house (PRN 18706) are located on the N side of the shaft. A concrete structure on the NW side (PRN 18458) may also be associated with winding. A second concrete structure (PRN 18705) with two deep slots presumably supported the pump rods is located on the S side of the shaft. Various ironwork lies around the shaft area, including the winding wheel for the wooden A-frame. A winch complete with wheel and cable remains in an area of spoil to the N of the shaft. The shaft area is unsafe and a chasm of severe collapse to the E reveals deep workings.

3.5 Immediately to the N of the shaft complex, a wheelpit (PRN 18579) c.12.5 x 3.75m remains in a state of collapse with timbers and support rods in situ. The overshot wheel was fed from a reservoir (PRN 18580) via a wooden launder. The rock-cut reservoir was fed directly by the stream, which it dammed, and possibly also from the main leat (PRN 18576).

3.6 To the E of the shaft, two quarries (PRNs 18581 and 18630) presumably provided stone for construction.

3.7 The main leat also fed the larger wheelpit (PRN 18575), which is located SE of the shaft complex, separated by the modern farm track. Leat PRN 18577 provided an additional source of water, with a system of wooden launders carrying the water to the overshot wheel. The wheelpit, cut into the rock face, is c.18 x 2.95m wide. The 1860 Mining Journal reported the cutting of the wheelpit, "nearly half of the wheelpit is cut out of solid rock which will save the expense in masonry work". In November 1860, The Mining Journal (Vol.31) reported the purchase of a 40ft pumping wheel from Esgairlle Mine, presumably for this large wheelpit. A letter (DD/WY/5352) dated 13.1.1859 from Captain Pearce to Williams refers to the sum of two to three thousand pounds being invested in new machinery. In 1873, a new 60ft wheel was installed (Mining Journal, July 1873, Vol.43). The surrounding timber framework survives with iron support rods in situ. The balance box, which acted as a breaking device for the pump rods, was sited on the S side of the wheelpit indicated by the rock-cut depression (PRN 18629). The N side of the wheelpit shows scouring on the masonry, where the crankshaft connected to the pumping rods once turned. The pier-base (PRN 18703) located between the shaft and the wheelpit presumably supported the pump rods. The 1860s-1880s mining operations were directed by William Lefaux, until he died penniless in 1888, when mining operations were abandoned until 1900.

3.8 The ore was brought out from the level (PRN 18566) which was driven in northwards from an area of quarrying (PRN 18567), probably for stone for the mine buildings. The ore was transported S to the dressing floor areas.

3.9 The early dressing floor area (PRN 18562) appears to have been platformed on timber supports above the natural bed of the stream. Spoil heaps remain on the west bank of the stream in this area and above them is a bank of ore-bins (PRN 18565). The ore was brought out of the level (PRN 1856) and transported to the ore-bins via tramway PRN 18569. The OS map of 1963, presumably based on a much earlier survey, suggests that the stream was diverted behind the ore-bins.

3.10 In 1846, a wheelpit housed a 12 x 2ft breast shot wheel (Bick 1990, 27) which is reported to have poorly powered the pitwork, crushing and early dressing machinery. A small stone-built wheelpit c.11 x 3.3m (PRN 18561) is located on the early dressing floor area (PRN 18562) on the E bank of the stream partly cut into bedrock, with the remains of its adjoining crusher house (PRN 18632). It appears to have been fed by a leat (PRN 18563) whose source is the storage reservoir (PRN 18564) fed by leat PRN 18570 dammed on the Nant Iago stream. An early leat (PRN 18633) may be associated with this reservoir but is cut by the later quarry. Adjoining the N wall of the wheelpit are the basal remains of the crusher (PRN 18632), which was loaded via a possible tramway.

3.11 S of the wheelpit, a collapsed level (PRN 18560) is located, presumably for bringing ore out to the early dressing floors below track PRN 18585 which runs in to the northern end of the early dressing floors. Further downstream a possible collapsed adit (PRN 18559) is located below the second track (PRN 18586) which leads in to the early dressing floor area from the modern farm track. In April 1860, The Mining Journal (Vol.30) reported a new road being made to run one and a half miles out to Nantiago Mine from the main Llangurig to Aberystwyth Road, to transport ore and materials. The original road is the route of the modern farm track and probably entered the mine at the early dressing floor area as track PRN 18586. A bridge and a date-stone remain along the route.

3.12 The new Nantiago Mining Company was registered in 1900 and a few months later The Mining Prospectors Syndicate bought shares, providing an increase of capital. In 1900, a new 56ft pumping wheel was erected by John Mills & Co. of Llanidloes and a new three-storey processing mill (see Plate 8/9). The wheel was erected at the large wheelpit (PRN 18575), replacing the previous 60ft wheel. The new dressing plant (PRN 18556) and crusher house (PRN 18557) remains downstream of the old dressing floor area. A Crossley Gas Engine was installed on site in the early 20th century to assist the pumping wheel (Bick 1990, 58). The mine site was sold to Llanidloes Mining and Machinery Company Ltd in 1913 and mining continued during the war.

3.13 Documentary evidence for the new plant lists 2 pelton wheels, stone breaker, rolls, trommels and 6 four-compartment jigs (Bick 1990, 58). The dressing floor area (PRN 18556) is platformed above the stream, and evidence remains of the stream being culverted and diverted away from the timber platforms. The high level of the stream in winter has washed debris over the processing area masking the features. Much of the machinery and support rods remain in situ on the wooden floor area. One collapsed trommel remains visible and others are now covered by debris brought down by the stream as the water level has risen. A concreted floor area c.12.75 x 7m on the E side of the dressing floor has several support rods in situ.

3.14 A pelton wheel survives in situ supported by a timber frame above the stone and concrete wheelpit (PRN 18635). The wheel presumably powered the crushing rolls by belt drive. Parts of a second pelton wheel lie on the dressing floors. Power was provided by water under pressure of gravity via iron pipes. The primary source was from leat PRN 18572, which terminates in a wooden tank (PRN 18636). From there water was sluiced either into the iron pipe (PRN 18636) or diverted to flow directly into the stream via leat PRN 18574. A track (PRN 18634) runs out to service the sluice. An additional source of water was provided, when pressure was low, from the main leat (PRN 18576) via a second iron pipe (PRN 18573), although this would divert water from the pumping wheelpit. The high pressure wheels powered all the machinery at the new plant.

3.15 The crusher house (PRN 18557) stands on the W bank of the stream. The crusher complex, constructed in stone and concrete, forms part of the three-storey processing mill built in 1900, and remains fairly intact although much of the stonework has collapsed. Ore was brought in to the top of the crusher house along the tramway (PRN 18569), which can be traced from the main level (PRN 18567). A rock-cut stairway leads to the upper floors of the building from the wooden floors of the pelton wheel area. An original mine track (PRN 18587) runs downhill towards the pelton wheel site from the modern track.

3.16 Beyond the S wall of the crusher house a platformed area contains the remains of wooden jiggers (PRN 18558).

3.17 The wooden launders (PRN 18698) which appear to have carried slurry from the processing area to the settling pits (PRN 18553) remain fairly intact. The launders follow the line of the stream passing a platform area (PRN 18555) whose function is undetermined.

3.18 On the W bank of the stream, downstream of the dressing floor, two large spoil tips of jig waste remain alongside the jig platforms (PRN 18558). Immediately above the northernmost tip are a run of three small settling pits (PRN 18554). The slimes are directed from the lower pit S to the Nant Iago stream via leat PRN 18700.

3.19 A leat (PRN 18574) which emerges from the pelton pipeline sluice enters the Nant Iago at the same point. Several cast-iron pipes, similar to the pelton pipes remain in along the line of the leat. Their function is undetermined. A short length of leat (PRN 18701) runs parallel to PRN 18574 as it reaches the stream.

3.20 Two rectangular settling pits c.12.1 x 5.4m and 10.5 x 9.7m (PRN 18553) are located on the SE bank of the Nant Iago stream at the S end of the site.

3.21 A concrete capped shaft (PRN 18552) remains fenced off on the southern extremity of the site, and is probably the air shaft.

3.22 Three building platforms (PRN 18571, 18716 and 18717), which include the foundations of the mine manager's house or office and possible stores are located on a level terraced area to the NE of the large wheelpit (PRN 18575). A track (PRN 18707) runs downhill to the front of the buildings from the modern farm track. An area of quarrying (PRN 18582) may have provided stone for the mine buildings. Barrack housing was erected further downstream on the former site of the Wye Valley Mines (PRN 18979 and PRN 8474) to provide lodging for itinerant miners.

3.23 Track PRN 18584 runs towards the basal remains of the smithy (PRN 18568) c.11.5 x 4m and continues towards the wheelpit PRN 18575. To the north of the modern farm track, the track that runs out to Engine Shaft appears to be a continuation of PRN 18584.

4. Conclusions

4.1 The surviving remains would appear to belong to two main periods of activity. Features clearly belonging to the earlier phase, dating c. 1846 to 1880s, relate mainly to the original dressing floors and consist of the ore-bins, crusher and wheelpit and adjacent platforms, together with winding and pumping equipment associated with the main shaft. The later phase consists of the substantial processing plant of 1900, together with its ancillary features. This structure is a rare survival of a late machine driven mill and is the best preserved within the Powys orefields. Accordingly, it is recommended that the whole mine site should be considered for protection as a Scheduled Ancient Monument.
(CPAT Metal Mines Survey - ground survey)

As previously described. (CPAT Tir Gofal assessment, 2003)

Sources :
Bick, D E , 1977 , The Old Metal Mines of Mid Wales 4
Bick, D E , 1980 , title unknown - Montgomery Metal Mines list , Archaeology in Wales : 36 : 83
Bick, D E , 1990 , The Old Metal Mines Of Mid-Wales
Bull, D E , 2002 , Tir Gofal Management Plan: Heritage Management Information (HE1). Glenrhyd, Llangurig - E/08/2701
Clwyd Powys Archaeological Trust , 1983 , Site visit record - PRN5944
Clwyd Powys Archaeological Trust , 1984 , CPAT Project Archive
Clwyd Powys Archaeological Trust , 1984 , Site visit record - PRN5944
Foster-Smith, J R , 1978 , The Mines of Montgomeryshire and Radnorshire
Jones, J A & Moreton, N J M , 1977 , The Mines and Minerals of Mid-Wales
Jones, N W and Frost, P , 1996 , Powys Metal Mines Ground Survey 1994 ( © Clwyd Powys Archaeological Trust)
Jones, O T , 1922 , Lead and Zinc. The Mining District of North Cardiganshire and West Montgomeryshire
Ordnance Survey , 1885 , OS map
Rees, D M , 1969 , title unknown - Van Mine
Sophie Watson , 2013 , Nantiago Mine, Glastir HEF Report ( © CPAT)
Williams, C. J., & Bick, D , 1992 , List of metalliferous mine sites of industrial archaeological importance

Events :
128490 : Nantiago Mine, Glastir HEF Report (year : 2013)
123076 : Powys Metal Mines, topographical survey 1994 (year : 1994)

Related records
CPAT Historic Environment Record (HER) 5944
106946

Compiled date : 31-12-1984


Images :



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, 2025 (and in part © Crown, 2025). 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.

April 22, 2025, 9:15 am - File produced for Archwilio from CPAT's Regional HER.
Clwyd-Powys Archaeological Trust, The Offices, Coed y Dinas, Welshpool, Powys, SY21 8RP
tel (01938) 553670, email her@cpat.org.uk, website www.cpat.org.uk

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