The Union showing is located on the northern shore of Knight Inlet opposite Adeane Point. The area is underlain by a belt of Upper Triassic Karmutsen Formation metamorphosed volcanic rocks con- tained in the Jurassic to Cretaceous Coast Plutonic Complex. The lithologies consist of thinly layered, biotite schist or phyllite, porphyritic greenstone and thin intercalations of light-weathering quartzite. The greenstone is commonly schistose and heavily epido- tized in narrow zones.

The mineralization is composed of cubes of pyrite disseminated in quartz veins. Trace gold and silver was identified from assay samples (Minister of Mines Annual Report 1919, page 213).