The Nantiago mine workings extend for over half a kilometer along the Nant Iago stream. Contains the highest concentration of in situ machinery and other dressing floor features found in the region

The surviving remains of the mine include an uncapped engine shaft with part of the pump rod still in place, 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, a crusher house, and culverts. Additional remnants include some of the Pelton water wheels, wooden jiggers, wooden launders, settling pits, building platforms, a smithy, and dams that diverted water to feed the leats—one of which was at least two miles long. Numerous tramways are also present. A miners’ barracks, a store shed, a mine office, and a magazine still exist but are poorly preserved.

The Nantiago mine primarily extracted lead, operating between 1846 and 1917. The geological composition of the site consists of Ordovician Upper Van mudstones and grits. The main vein follows an ENE-WSW strike, while a north-south cross vein contains calcite with galena and sphalerite. The mine’s workings include a shaft, a deep adit, and two additional visible levels, along with numerous small exploratory trials on the surrounding slopes.

Transport infrastructure at the site includes several tramways used to move ore from the adits to the dressing floors. Power was primarily supplied by water from the Nant Iago, which was diverted via leats to drive three waterwheels and two Pelton wheels for pumping, ore drawing, and processing. The largest pumping wheel had a diameter of 60 feet. A cast-iron Pelton wheel remains intact and in situ on the dressing floor. Additionally, a small gas engine was once located here. The high-pressure pipeline that supplied water to the Pelton wheels can still be traced as a scar running along the hillside.

In 1900, a three-story processing mill was constructed, powered by two Pelton wheels. The mill featured a stone breaker, rolls, trommels, and six four-compartment jigs, replacing an earlier dressing floor about which little is known. The lower level of the 1900s mill remains partially intact, with much of its original processing machinery either still in place or scattered throughout the site. Several wooden structures have survived, along with a collapsed trommel screen, a Pelton wheel, part of a belt-driven drive shaft, and a small feeder cone. Additional machinery may still be buried within the main structure.

Other notable features at the site include the remnants of a miners’ barracks (SN82558631), a store shed, a mine office, and a magazine, though these structures are in poor condition. At the top of the main shaft, cast-iron winding wheels from the shear legs and the adjacent cage winder are still present, along with other debris. A cast-iron winding drum with a gear wheel and rewound cable is partially buried in a spoil tip near the shaft (SN82478638).

This site is particularly significant due to two key features. Firstly, the 1900 processing plant is the best-preserved example of its kind in the West Montgomeryshire orefield and contains the highest concentration of in situ machinery and dressing floor elements in the area. Secondly, remnants of the engine shaft winding gear survive, making this the most intact assemblage of such equipment within West Montgomeryshire. These factors make the Nantiago mine an important historical and industrial site within the region.

Total production: 1709 tons lead ore, 1929 tons of blende