Drum Quarry (GR SH735431) lies about 1.5 miles to the south east of Manod Mawr, and a little to the north of Llyn Morwynion, near Llan Ffestiniog. It was a small concern, developing underground from surface working, and dating from the 1860s. Work was sporadic on the site, and only about 20 men were employed, producing some 500 tons a year.
Relics of the internal tramway exist, as do the drumhouse, incline, and mill buildings.
An aerial photo of Drum Quarry, taken in 1996, can be found here.