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Pearl Engine House

A Grade II Listed Building in Amlwch, Isle of Anglesey

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Latitude: 53.3909 / 53°23'27"N

Longitude: -4.3359 / 4°20'9"W

OS Eastings: 244761

OS Northings: 390775

OS Grid: SH447907

Mapcode National: GBR HMNQ.YDS

Mapcode Global: WH427.C1J8

Entry Name: Pearl Engine House

Listing Date: 12 December 2000

Last Amended: 12 December 2000

Grade: II

Source: Cadw

Source ID: 24458

Building Class: Industrial

Location: Located in a prominent position on the extreme north-east side of Parys Mountain. Accessed via a minor road leading W off the A5025.

County: Isle of Anglesey

Town: Amlwch

Community: Amlwch

Community: Amlwch

Locality: Parys Mountain

Traditional County: Anglesey

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The Pearl Shaft Engine House was constructed in the early C19 for the Mona Mine, to house an 18" Cornish Beam Engine, which was used for pumping water up the 600'(182.9m) deep Pearl shaft. The design is based on a Cornish engine house. The engine was in operation by 1819, when it was visited and described by the physicist Michael Faraday. The water in the shaft sump was lifted a short distance to a cistern by lift pump, from where a force pump pushed it up the shaft to another cistern, where the process was repeated. The Engine House fell into disuse when the mine ceased operating in 1904, was stripped of machinery and steadily became derelict. In 1992 the Welsh Mines Preservation Trust was formed and one of its first objectives was to promote the importance of the engine house as an industrial building and to raise funds and support to save the building from further collapse. In 1993 permission to proceed was granted by the landowner, the Marquis of Anglesey and consolidation work was carried out in mid to late 1990s.
Copper ore had been extracted from Parys Mountain from the Bronze Age onwards, although operations before the late C18 were small-scale and piecemeal. In 1768 a rich deposit of copper ore was discovered, and the two opencast mines of Parys and Mona became the largest producers of copper in the world, with over 3000 tons(3048 tonnes) of copper produced annually between 1773 and 1785. Production levels had peaked by 1800, after which time production fluctuated. The underground workings were expanded after 1811, under the direction of Cornish mine captains. There was a brief boom in the early 1830s, but by the end of the century less than 500 tons(508 tonnes) was being raised annually. By 1904 the mines had closed, due to the competition from cheaper copper imported from America and Africa. The total production of copper from the area during the period between 1768 and 1904 has been estimated at 3.5 million tons(3.6 million tonnes) of ore, from which 130,000 tons(132,080 tonnes) of copper metal was recovered.


Engine house, roughly square in plan, with a gabled roof. Formerly attached to the N side was a larger, rectangular, boiler house with chimney (now demolished); to the S is the Pearl Shaft (now capped), and to the SW is the area of the capstan pit and rope channel. Rubble walls, generally 0.6m thick, although the bob wall to the S, which supported the engine beam, is 1.2m thick below the point where the beam fulcrum is located. The roof was formerly slated. Ground floor openings to each elevation with replaced timber lintels; Tall brick arched opening set high in the S elevation for bob mount.


The N half of the floor contains the mountings for the engine cylinder, the cylinder block. The S part of the floor holds the cataract pit, which is about 2m lower than the cylinder block level.

Reasons for Listing

Included, notwithstanding condition, as an early C19 engine house which formed an important component of the industrial copper mining complex at Parys Mountain, at one time the greatest producer of copper in the world. The engine house forms a prominent feature within the landscape, is a rare survivor of its type and unique on Anglesey.

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Other nearby listed buildings

  • II Parys Mountain Windmill
    In an isolated location, set back from the SE side of the B5111 running S out of Amlwch. The windmill is located close to the highest point of Parys Mountain, to NE of the remains of the Parys Mines.
  • II Parc Mawr
    Set back from the NE side of the A5025 on the SE approach to the town of Amlwch; c1.5km SE of the Church of St Eleth.
  • II Capel Bozrah
    At the NW end of the village of Pen-y-Sarn, the chapel is set back from the road at the head of a symmetrically laid-out group including chapel house and school room.
  • II School Room and Store at Capel Bozrah
    At right angles to the chapel, forming the right hand range of a symmetrically planned group of 3 associated buildings.
  • II Railings to yard at Capel Bozrah
    Enclosing the yard in the front of the chapel, running between Ty Capel Bozrah and the school room/store building.
  • II Ty Capel Bozrah
    At right angles to the chapel, forming the left hand range of a symmetrically planned group of 3 associated buildings.
  • II Melin Adda
    Set back from the N side of Ffordd Tanybryn, c200m due east of Ysgol Syr Thomas Jones in Pentrefelin.
  • II Ty-newydd
    Located at the E side of the A5025 on the way out of Amlwch to the south. The cottage lies SW of the roundabout at Cross Ways and is at the junction with the turn off to Bod-Ednyfed-bach.

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