Nantiago Mine

Overview

A lead and zinc working on the eastern flank of Plynlimon, in the Hafren Forest, worked in repeated bursts between before 1846 and 1918 and powered by water diverted from the Nant Iago via a network of leats.

History

Nantiago Mine -- also recorded as Plynlimmon Mine -- lies on the eastern flank of the Plynlimon range, in what is now Hafren Forest. It was already at work before 1846, when surviving records begin, and was worked again in 1853 and 1860-64; it was reopened in 1872 and developed until 1888, and worked once more from 1900 until around 1918. William Lefeaux is recorded working the mine, though a complete list of its operators is not recorded. Recorded production totalled 1,709 tons of lead ore and 1,929 tons of zinc ore.

The Trust's survey and the Geological Conservation Review explain what the bursts of working left. Leats off the Nant Iago drove three waterwheels, the pumping wheel growing to 60 feet across, and in 1900 a new three-storey mill was built, driven by two Pelton wheels, with a stone breaker, rolls, trommels and six jigs; one cast-iron Pelton wheel still stands on the dressing floor and the mill's ground floor keeps much of its machinery, the best-preserved plant of its kind in the West Montgomeryshire orefield. The shaft was eventually sunk to 70 fathoms below adit, and the whole recorded output over seventy years was 1,709 tons of galena, 1,651 oz of silver in the years it was desilvered, and 1,929 tons of zinc concentrates. The end came not with the ore but with the price: the sale of Government metal stocks after the Armistice broke the market, and a remote mine paying dear for haulage could not survive it.

Geology

Lead and zinc of the upper Twymyn ground; the vein is not named on the record.

Workings

Water diverted from the Nant Iago via a network of leats drove three waterwheels and two Pelton wheels, used for pumping, ore-drawing and processing. Surviving remains include an uncapped engine shaft with part of its pump rod still in place, the foundations of a winding or drum house, wheelpits, reservoirs, dressing floors, ore bins, a crusher house and culverts.

Closure

Worked in several separate bursts, the last from 1900 to about 1917-18; the mine, one of the last in Central Wales to close, was finished by the collapse in metal prices after the Armistice and the cost of haulage to so remote a site.

What remains

A well-preserved multi-period lead and zinc mine, its surface remains recorded in detail by an Archaeology Data Service survey of the site's leat system.

An uncapped engine shaft with part of its pump rod, the winding-house foundations, wheelpits, reservoirs, dressing floors, ore bins, the crusher house and culverts; the 1900 three-storey mill's ground floor with a cast-iron Pelton wheel, a collapsed trommel and drive shaft in place; the poorly preserved barracks, store, office and magazine; and the shear-leg winding wheels and a part-buried winding drum by the shaft.

Related mines

• Plynlimmon Mine — The two are neighbours in the same upland orefield and share a name problem: Nantiago's own older name was Plynlimmon, which is why this mine has to be distinguished as the one west of the mountain.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• Recorded production totalled 1,709 tons of lead ore and 1,929 tons of zinc ore. ¹
• Water from the Nant Iago, diverted via leats, drove three waterwheels and two Pelton wheels for pumping, ore-drawing and processing. ²
• Nantiago was worked in several separate bursts: before 1846, in 1853, in 1860-64, from 1872 to 1888, and from 1900 to around 1918. ¹
• A winze sunk beneath the existing workings reached a 48-fathom level around 1890, the deepest level recorded at the mine, where a report by Captain John Roberts of Nantgarw (dated 18 September 1895) described a rib of galena 4 to 7 inches wide. ³
• The mine's own spoil tips are protected as part of the Nantiago Site of Special Scientific Interest, notified in 2002 for the mineralisation they display -- a 2.67-hectare site on the eastern flank of the Plynlimon range. ⁴
• The Clwyd-Powys Archaeological Trust records Nantiago (HER 5944) at SN 8260 8630 in Llangurig, worked for lead 1846-1917 in Ordovician Upper Van mudstones and grits, the main vein striking ENE-WSW and a north-south cross vein carrying calcite with galena and sphalerite. A shaft, a deep adit and two other levels are visible with numerous trials on the slopes; leats from the Nant Iago fed three waterwheels, the pumping wheel reaching 60 feet in diameter, and two Pelton wheels, one cast-iron Pelton wheel still in place on the dressing floor, with a small gas engine formerly there too. A new three-storey mill of 1900, driven by the Pelton wheels, had a stone breaker, rolls, trommels and six four-compartment jigs; its ground floor survives with machinery in place, and miners' barracks (SN 8255 8631), a store, office and magazine survive poorly, with the winding wheels from the shear legs in the shaft top and a winding drum part-buried in the tip. ⁵
• Between 1846, when mining in earnest began, and 1917 the mine produced 1,709 tons of galena, desilvered in some years for 1,651 oz of silver, and 1,929 tons of sphalerite concentrates (Jones, 1922); it was eventually sunk to 70 fathoms below adit. One of the last Central Wales mines to close, working through the First World War, it fell to the collapse in metal prices caused by the sale of Government stocks after the Armistice, compounded by the cost of haulage to so remote a site; its tips are the finest demonstration in the Central Wales orefield of the late 'Pennine-type' mineralisation, and the property was later considered, and rejected, as a source of white calcite. ⁶
• Buddlepit records Nantiago, also Lower Van or Plynlimmon, as a lead mine worked 1846-1917 at 52.4612999, -3.7282021 (SN 8268 8622), 430 metres up on open-access land, with the region's highest concentration of in-situ machinery and dressing-floor features. ⁷

Sources

1. (secondary) Nantiago Mine (Plynlimmon Mine) — mindat.org
2. (secondary) Nantiago Mine, main leat — Archaeology Data Service
3. (primary) The Plynlimon Mines, Ceredigion, Wales, U.K.; an integrated evaluation from new surface geological mapping and contemporary subsurface documentation — James, D.M.D. & Hall, G.W. (2004), Mining and Resource Geology Symposium
4. (primary) Nant Iago Lead Mine; Plynlimmon Lead Mine (NPRN 34004) — Royal Commission on the Ancient and Historical Monuments of Wales
5. (primary) Powys Metal Mines Survey: Nantiago (Clwyd-Powys Archaeological Trust, HER 5944) — Clwyd-Powys Archaeological Trust
6. (primary) Nantiago Mine, GCR site (Geological Conservation Review vol. 36, via GeoGuide) — Joint Nature Conservation Committee
7. (secondary) Nantiago (Buddlepit Mine Database) — Buddlepit / Mining History Trust

Record created: 1 September 2026 · Last researched: 24 September 2026