Gilfach Quarry is located in woodland on the southern edge of the village of Llangolman. It constitutes a series of shallow workings on either side of the river Wern. It has been operating since at least the later nineteenth century when it appears on the Ordnance Survey first-edition 25-inch map, and was still working on a small scale as recently as the late 1980s. Although the product was of variable quality, the slate was valued for its green colour, 'rustic' slates being offered as a speciality.
The site has been much disturbed by recent re-working but a few buildings survive, some in re-use, along with some tramway formation.

Sources:
D.Gwyn, Welsh Slate: the Archaeology and History of an Industry (RCAHMW 2015), pp.18 (Fig.28), 29 & 34.
OS County Series mapping: sheet Pembrokeshire XVIII.11, edition of 1890.
A.J.Richards, A Gazeteer of the Welsh Slate Industry (1991), p.231.

David Leighton, RCAHMW, 4 February 2015