Between Moel Hebog and Moel yr Ogof in Cwm Pennant. Marked on OS map. Also known as Cwm Llefrith. Large entranced adit and cavernous stopes. A shaft higher up the hillside also communicates. There are a number of smaller trial workings.
| Year | Activity |
|---|---|
| 1837 | Lease granted to William Morgan Buckingham. Taken over on Buckingham’s death by Henry Marshall. |
| 1847 | 21 year lease granted to Marshall, guaranteeing to keep 8 men working for 8 months of the year. |
| 1854 | Was being worked alongside with Dinas Great Consols in what was largely a scam |
| 1883 | Worked as Cwm Llefrith by 3 partners |
| 1886 | Take note from Crown to form Moel Hebog Copper Mining Co. Ltd |
| 1888 | Name changed to Glistening Valley, 44 men being employed - half underground. |
| 1889 | Liquidised |
summarised from Bick
Publications (2)
- Bick, D.E. (2003); Old Copper Mines of Snowdonia, The; pp. 28-32
- Jarratt, Tony (1981); Logbook 2; 121 pages
