The Friends of Cwmorthin Slate Quarry

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Hello and Welcome to the Friends of Cwmorthin Website

The Friends of Cwmorthin (FOC for short!) represents a small group of individuals interested in the history, exploration and preservation of the historic Cwmorthin Slate Quarry, near Blaenau Ffestiniog, North Wales. It is generally a quarry in name only, but a mine in nature, as almost all of the slate extraction was underground. Together with its neighbour (Oakeley Slate Quarry), with which it eventually merged, it is considered both the largest and deepest slate mine in the world.

What's New?

We've uploaded some old archive documents to read and are adding more soon!

The many miles of tunnels and caverns, the majority of which are between 100 and 150 years old, can be explored today by suitably experienced and equipped persons without cost or unnecessary hindrance. It is a fascinating environment created by the life long labours of thousands of highly skilled Welsh Rock Men and Miners. More >

Would you like to explore Cwmorthin?

Cwmorthin Slate Quarry is available to all who wish to explore it. The two main entrances are both locked to discourage unequipped passers-by from entering the workings. However, keys are freely available to borrow by suitably experienced and equipped persons. Please see the How to Visit page for more information.

Would you like to join the Friends of Cwmorthin?

The FOC comprises entirely of volunteers who enjoy exploring, preserving and documenting the mine. Joining the group is free and open to anyone, anywhere. Discussion within the group and the organisation of projects and work days all happens within the Members Area of this website. More >

Do you have any spare materials?

We're always desperately looking for donations of surplus materials such as steel bar, RSJ's, cable, bolts, acro-props, scaffold bars and fixings, pipes, heavy timber and tools. If you have anything of this nature that you might be able to spare - please get in touch!