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Gwynfynydd Mine (Gwyn Mine; Morgan Mine; Mount Morgan Mine; British Gold Fields), Ganllwyd, Dolgellau Gold Belt, Gwynedd, Wales, UK

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Latitude & Longitude (WGS84): 52° 50' 13'' North , 3° 52' 30'' West
Latitude & Longitude (decimal): 52.83706,-3.87519
UK National Grid Reference:SH737283
Other regions containing this locality:Snowdonia National Park, Wales, UK
Köppen climate type:Cfb : Temperate oceanic climate
Other/historical region names associated with this locality:Merionethshire

Second to Clogau in terms of gold output, Gwynfynedd ranked with Clogau and Glasdir, the latter primarily a copper mine, as one of the largest and richest mines in the Dolgellau gold belt. The remains of the Gwynfynedd mill are at OS grid ref. SH 735274.

Up to 20 parallel lodes in five main groups have been recognised: the Chidlaw, Collett, James, Harvey and Big lodes. The greatest thickness attained in a single vein being 20 feet in the Chidlaw lode. All strike nearly east-west and have been traced for up to a mile and a half.

Although the Gwyn tribute lease appears in the mineral statistics for 1911-12, it was characterised by low employment and low yields from a substantial tonnage of ore; it has been suggested that this was the bulk of the output of Prince Edward Mine after selected ore had been processed at Prince Edward.

Total returned production between 1862 and 1916 was 98,842 tons of gold ore yielding 40,054 ounces of gold (about half of that produced by Clogau). After the main phase of mining ended, the mine operated intermittently and on a much smaller scale until almost the present day. In recent times both the Clogau and Gwynfynydd mines have been exploited by companies taking advantage of the high premium payable for Welsh gold in the jewellery market.

Goldmining in Western Merioneth, T. A. Morrison (undated)
The Gold Mines of Merioneth, G.W. Hall (undated)

Mineral List

13 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

419.2 - 443.8 Ma

ID: 3185808
Paleozoic sedimentary rocks

Age: Silurian (419.2 - 443.8 Ma)

Lithology: Sedimentary rocks

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

Tremadocian - Late Cambrian
477.7 - 501 Ma

ID: 2032019
Upper Cambrian, Including Tremadoc

Age: Paleozoic (477.7 - 501 Ma)

Lithology: Mudstone, siltstone and sandstone

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

485.4 - 541 Ma

ID: 3145855
Cambrian sandstone

Age: Cambrian (485.4 - 541 Ma)

Lithology: Sandstone

Reference: Asch, K. The 1:5M International Geological Map of Europe and Adjacent Areas: Development and Implementation of a GIS-enabled Concept. Geologisches Jahrbuch, SA 3. [147]

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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