Gaewern Slate Quarry is depicted on the Ordnance Survey County Series second edition 25-inch map of 1901. The quarry was amalgamated with Braichgoch Slate Quarry and Abercorris Slate Quarry.

Workings at Gaewern were underground with some open working, established in about 1820. The quarry developed considerably after its connection to the Upper Corris Tramway by an incline passing under the main road.