The Gordon River showing is located south of the Gordon River logging camp, 25 kilometres southwest of Cowichan Lake.

A limestone mass, of the Upper Triassic Quatsino Formation (Vancouver Group) extends west-northwest from Gordon River for 2 kilometres and is 1 to 1.5 kilometres in width. The limestone is underlain by basaltic volcanics of the Upper Triassic Karmutsen Formation, Vancouver Group which outcrop along the southern margin of the deposit. The limestone is in fault contact with Karmutsen and Lower Jurassic Bonanza Group volcanics to the north. Bedding within the limestone mass dips 25 to 45 degrees north.

The limestone is fine grained, dark grey to black on fresh surfaces, weathering to medium to light grey. It is generally high calcium in composition, but does contain a few magnesian beds. A sample of randomly collected chips taken along a 60 metre long road- cut next to the Gordon River contained 54.72 per cent CaO, 0.21 per cent MgO, 1.30 per cent insolubles, 0.24 per cent R2O3, 0.17 per cent Fe2O3, 0.02 per cent MnO, 0.02 per cent P2O5, 0.068 per cent sulphur and 43.22 per cent ignition loss (Minister of Mines Annual Report 1966, page 270, Sample 6).

Matrix Marble Corp. produces Black Carmanah from the area.