| Name | Location | County | Country | Power source | Type | Function | River |
| Slate mill, Drum Slate Quarry, Blaenau Ffestiniog | Blaenau Ffestiniog, Ffestiniog | Merionethshire | United Kingdom | Water | Watermill | Quarry mill/wheel, Slate mill | Gamallt |
| Name | Location | County | Country | Power source | Type | Function | River |
| Slate mill, Drum Slate Quarry, Blaenau Ffestiniog | Blaenau Ffestiniog, Ffestiniog | Merionethshire | United Kingdom | Water | Watermill | Quarry mill/wheel, Slate mill | Gamallt |