The Tagish Coal occurrence is reported to occur on the south side of Graham Inlet, about 8 kilometres southwest of Taku Landing and 13 kilometres west of the community of Atlin.
The area south of Tagish Inlet is underlain primarily by argillite, greywacke, and wacke of the Lower Jurassic Laberge Group (Inklin Formation). Overlying this and exposed at higher elevations are conglomerate and sandstone of the Lower Eocene Sloko Group. North of Tagish Lake are undifferentiated rocks consisting mainly of volcanics of probable Triassic age.
Identified from Paper 1986-5 (Coal in Northwestern British Columbia), the existence of the coal showing has not been confirmed.