The Tzahny Ridge occurrence is a cluster of coal seams on an alpine ridge approximately 3 kilometres west of the peak of Tzahny Mountain in the Skeena Ranges about 170 kilometres northeast of the community of Stewart. They were identified, trenched and sampled by Dawson and Ryan in 1989 (Geological Survey of Canada Open File 2555). The seams range in thickness from 1.25 to 22.7 metres. Coal is of anthracite rank (vitrinite reflectance values range from 4.60 to 5.02 per cent). However, Dawson and Ryan report that the coal quality is "poor".

The Tzahny Ridge coal occurrence is hosted by the Upper Jurassic to Lower Cretaceous Skelhorne assemblage of the Bowser Lake Group. The Skelhorne is a deltaic assemblage, and includes thinly intermixed and varicoloured siltstone, sandstone, and conglomerate, with or without coal (Geological Survey of Canada Open File 5571).

Dawson and Ryan (Geological Survey of Canada Open File 2555) reported that the "structural complexity of the area" of Tzahny Ridge precluded determination of the total number of seams present, but it appears that there are at least five. The strata are tightly folded into closely-spaced anticline-syncline pairs with axial planes striking about 315 degrees (Geological Survey of Canada Open File 5571).