Marchlyn Mawr, Llanberis, Gwynedd (Caernarvonshire), Wales, UK
The natural lake Marchlyn Mawr has been dammed to form the upper reservoir of the Dinorwig Pumped Storage Scheme, the largest pumped storage hydroelectric scheme in Europe at the time of its construction in 1984 (see also Dinorwig Quarry, the site of the lower reservoir).
UK Grid Reference: SH616619
Fibrous, radiating aggregates of thomsonite occur here infilling vesicles to 20 mm in diameter in the Marchlyn Dyke; an olivine dolerite of Palaeogene age.
Williams, D., 1930. The geology of the country between Nant Peris and Nant Ffrancon (Snowdonia). Quarterly Journal of the Geological Society of London, 86, 191-232.
Williams, D., 1924. On two olivine-dolerite dykes in Snowdonia. Proceedings of the Liverpool Geological Society, 14, 38-47.
1 entry listed. 1 valid mineral.
The above list contains all mineral locality references listed on mindat.org. 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 mindat.org 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.
This page is currently not sponsored. To sponsor this page click here.
|Fade toolbar when not in focus||Fix toolbar to bottom of page|
|Hide Social Media Links|
|Slideshow frame delay||seconds|