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UK | |
| Day, Harry (1999) BMS Database, British Micromount Society. |
| Braithwaite, R.S.W. (1982): Pyromorphite, wulfenite and other minerals from the Bwlch-Glas mine central Wales. Mineralogical Record 13: 151-153 |
- Upper Llanfihangell-y-Creuddyn
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| Rust, Steve A. (2019) Minerals of the Frongoch Mine. Published by the author, 180 pages. ISBN 978-1-9162641-0-6. Day, Harry (1999) BMS Database, British Micromount Society. Green, D.I., Rust, S.A., Mason, J.S. (1996) Classic British mineral localities: Frongoch mine, Dyfed. UK Journal of Mines and Minerals 17, Rockbottom Publications. 29-39 |