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Slate Dressing Mill

A Grade II* Listed Building in Ffestiniog, Gwynedd

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Latitude: 53.0012 / 53°0'4"N

Longitude: -3.9186 / 3°55'6"W

OS Eastings: 271345

OS Northings: 346598

OS Grid: SH713465

Mapcode National: GBR 5Z.GW11

Mapcode Global: WH559.ST6L

Plus Code: 9C5R232J+FH

Entry Name: Slate Dressing Mill

Listing Date: 1 February 1996

Last Amended: 1 February 1996

Grade: II*

Source: Cadw

Source ID: 16888

Building Class: Industrial

Location: On the main Maenofferen level, a working underground quarry, high above Llechwedd.

County: Gwynedd

Community: Ffestiniog

Community: Ffestiniog

Locality: Maenofferen Slate Quarry

Traditional County: Merionethshire

Tagged with: Building

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History: The Maenofferen quarry opened in the early C19 and was developed and expanded by J W Greaves in the 1850s. In 1882 there is a recorded output of 8,494 tonnes (8,360 tons) of slate with 238 men employed. By the 1890s this had risen to an average of 1,422 tonnes (1,400 tons) and 400 men. The huge twin slate mills on the Maenofferen level are not shown on the 1888 O.S map, though graffiti exists from 1896, thereby allowing for a fairly close dating. Originally water-powered, the mills were converted to electric power c1906; the complex is still partly in use.

Exterior: Long twin-mill building (approximately 60m) of slate block construction with double slate roof; the N range is half-hipped to the W and has a corrugated iron E gable end, while the S range is half-hipped at both ends. Continuous catslide outshuts to long sides forming a flat-roofed connecting corridor in the centre, linking the two ranges. Plain skylights along each long side to light internal bays and 3 plain tin louvres to the N range. At the gable ends and the central conjunction of the ranges rail tracks enter through sliding boarded doors, allowing for supply of quarried slate and removal of both the finished product and the waste. These tracks continue along the entire length of the building internally and emerge through similar openings at the opposite end. Locomotive shed extension to the W end of the S range with small slate chimney and entrance to the S return; various blocked openings along the long sides of the mill.

Interior: Each of the ranges is 26 bays long and all original king-post trusses are retained. The N range is currently unused, though it contains various Late C19 Greaves patent rotary dressers (developed in the 1850s and patented in 1886). In addition a B6 slate planer by Turner Bros. of Newtown survives in situ . In the S range the original overhead transmission shafting is in use operating 12 belt-driven Greaves rotary dressers as before; 13 dressing alcoves are still used (on the S side), though most of the others remain, some with slate slab partitions and all with wooden L-shaped stacking benches. In the central (13th) bay, walled off from the rest of the bays, the former wheel pit, though the wheels have long been removed.

Listed Grade II* as an exceptional survival of a largely unaltered and still used late C19 slab mill.

Group value with other listed items at this exceptionally well preserved slate quarry.

References: A .J. Richards, A Gazetteer of the Welsh Slate Industry, 1991.
J.G. Isherwood, Slate From Blaenau Ffestiniog, 1988, 43.
D. Rh. Gwyn and A. Davidson, 'Gwynedd Slate Quarries', Gwynedd Archaeological Trust Report No. 152, (forthcoming).

External Links

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Other nearby listed buildings

  • II Smithy and Workshop Range
    Immediately NE of the dressing mill on the main level of Maenofferen, a working quarry high above Llechwedd..
  • II Booster Station
    Located immediately to the E of the slate dressing mill and S of the smithy/workshop.
  • II Former Engine House
    Located immediately behind the electric booster house on the main level, NE of the slab mill.
  • II* Powered Incline Drumhouse including chimney
    At the end of a short rock tunnel linking the main Maenofferen level with the underground incline 100m E of the slab mill.
  • II Former Weighbridge Hut
    Located immediately to the S of the powered incline drumhouse, at the mouth of the connecting tunnel to the main level; built against the rock facing the railtrack.
  • II Remote Incline Drumhouse
    Located approximately 150m NW of the slab mill on the main level of the quarry, on a bend and at the top of a long disused incline.
  • II Hydro-electric Powerstation
    Located 1km to the NW of the main Maenofferen level, in a sheltered hollow beneath the summit of Moel Bowydd; N gable into the rock.
  • II Tai Uncorn
    Set back behind a low walled garden on a slight rise at the NE end of the street.

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