Ancient Monuments

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Dyffryn Adda Copper Furnace and Precipitation Ponds

A Scheduled Monument in Amlwch, Isle of Anglesey (Ynys Môn)

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Latitude: 53.3957 / 53°23'44"N

Longitude: -4.3507 / 4°21'2"W

OS Eastings: 243796

OS Northings: 391333

OS Grid: SH437913

Mapcode National: GBR HMMQ.PVF

Mapcode Global: WH421.4XJ6

Entry Name: Dyffryn Adda Copper Furnace and Precipitation Ponds

Scheduled Date: 14 September 2000

Source: Cadw

Source ID: 1059

Cadw Legacy ID: AN135

Schedule Class: Industrial

Category: Copper mine

Period: Post Medieval/Modern

County: Isle of Anglesey (Ynys Môn)

Community: Amlwch

Traditional County: Anglesey


The monument consists of the remains of a reverberatory furnace and precipatation pits dating to the 19th century. The Mynydd Parys Copper Mines were by the eighteenth century the most productive in Europe, extracting ore by opencasting, underground working and precipitation. Dyffryn Adda furnace is the only identified reverberatory furnace for copper smelting surviving in Wales, which was the most important region in the world for copper production. Such furnaces were once common features in the copper processing industry of Wales. The associated precipitation ponds are the best surviving example of a method of extraction practised extensively on Mynydd Parys but nowhere else in Britain. They are believed to have been used from c1818 to c1958. Other features include buildings associated with the reverberatory furnace, including a derelict cottage and the entrance to the Dyffryn Adda adit from which the precipitate was derived.

The monument is of national importance as a unique survivor of reverberatory furnace technology in association with an important adit and precipitation ponds and for its potential to enhance our knowledge of industrial mining practices. It retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits.

The scheduled area comprises the remains described and areas around them within which related evidence may be expected to survive.

Source: Cadw

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