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Benallt Mine (Tyddyn Meirion mine; Ty Canol mine), Rhiw, Llanfaelrhys, Lleyn Peninsula, Gwynedd, Wales, UK

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Latitude & Longitude (WGS84): 52° 49' 14'' North , 4° 38' 20'' West
Latitude & Longitude (decimal): 52.82073,-4.63896
UK National Grid Reference:SH222281
Köppen climate type:Cfb : Temperate oceanic climate
Other/historical region names associated with this locality:Caernarvonshire

The Benallt mine was opened in 1886 and continued to produce manganese ore until 1894 when the site was abandoned.

Although separately owned, Benallt and the adjoining Rhiw Mine worked the same orebody and both surface and undergound workings were amalgamated. The north-east part of the orebody worked by the Rhiw Mine was Crown property whilst the larger Benallt Mine to the south-west was in private ownership.The distinction between the two mines on the ground is unclear (however, a large steam boiler remaining on the site is in the Rhiw Mine set).

The Benallt mine was reworked in 1904 as the Benallt No 2 mine when further reserves of manganese were delineated. However, the orebody appears to have been almost exhausted by 1914 and the company then turned their attention to The Nant mine, a more regular orebody on the coast that was located about 1 mile SSW of Benallt. Nant Mine lasted until 1925.

Benallt was reopened by the Ministry of Supply in 1939 to produce minerals for the war effort, this final working incorporating the Rhiw Mine together with the small Tyddyn Meirion (SH221277) and Ty Canol (SH220278) mines immediately to the south. Together with local men, Cornish tin miners, Welsh coal miners, and a contingent of the Royal Canadian Engineers (1941) were also employed. The main use of the latter being to drain old workings and to drill to locate other orebodies.

Bennalt mine was also one of the first to use a magnetometric survey to locate ore reserve. The survey indicated 3 anomalies, 2 of which produced 10,000 tons of manganese ore. The mine worked until the end of 1945.

The Benallt/Rhiw mines were linked to a jetty on the coast at the Nant Mine by a ropeway during the earlier working, this was later replaced by a 3-foot gauge railway.

Recorded output for Benallt, Rhiw, and Nant mines is estimated to be around 150,000 tons of manganese ore.

Given the linkage between the Benallt and Rhiw mines, it is likely that many of the minerals listed here for the Benallt Mine will also have occurred at Rhiw Mine. Whilst some specimens (e.g. the exceptional celsian and paracelsian found in 1911) can be related specifically to underground workings at Benallt Mine, given that no minerals are listed separately for Rhiw Mine, it appears that mineralogically at least, the two mines seem to be grouped together under the umbrella name of the larger Benallt Mine.

The parish of Rhiw has merged into that of Llanfaelrhys to the south.

Mineral List

37 valid minerals. 4 (TL) - type locality of valid minerals.

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on

456.5 - 470 Ma

ID: 2035266
Llanvirn Rocks (Undifferentiated)

Age: Ordovician (456.5 - 470 Ma)

Lithology: Mudstone, siltstone and sandstone

Reference: British Geological Survey. DiGMapGB-625. British Geological Survey ©NERC. [23]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License

This page contains all mineral locality references listed on This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


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Smith, W.C. & Claringbull, G.F. (1947): Pyrophanite from the Benallt Mine, Rhiw, Carnarvonshire. Mineralogical Magazine 28, 108-110.
Cotterell, T. (2008): The first British occurrence of feitknechtite at Benallt manganese mine, Rihw, Pen Llyn, Gwynedd, Wales. UK Journal of mines & Minerals, number 29 pp47-48.
Cotterell, T., Tayler, R. (2012): Epidote-(Sr) and piemontite-(Sr): two minerals new to Britain from Benallt mine, Pen Llŷn, Gwynedd, Wales. UK Journal of Mines and Minerals 33, 39-42.

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