The area of the Tony occurrence is underlain by andesite, basalt, tuff, breccia and limestone of the Lower Jurassic Bonanza Group. These rocks have been intruded by Jurassic granodiorite of the Island Plutonic Suite.
Epidote, chlorite and k-feldspar alteration are present at some contact locations and faulting is extensive.
Small veins contain pyrite, pyrrhotite, chalcopyrite, sphalerite and galena.