The Cob 3 showing is underlain by Pennsylvanian sedimentary rock of the Stikine Assemblage. The assemblage is intruded by Paleocene to Eocene granite and alkali feldspar granite of the Sloko-Hyder Plutonic Suite in contact a few kilometres to the west, and granodiorite of the Early Jurassic Cone Mountain Plutonic Suite, in contact with the Stikine rocks a few kilometres to the north and south.

A brownish orange, strongly gossanous zone with intense iron staining and with clasts of silty slate were observed just east of a narrow south to southeast trending brittle to sheared breccia zone cutting an area of phyllite, shale and phyllitic slate. A sample of this material assayed 8.2 grams per tonne silver, 0.11 gram per tonne gold and 0.1 per cent arsenic (Sample Q923652, Assessment Report 35895).

A brownish yellow breccia with iron oxide and carbonate alteration in silty slate formation assayed 0.077 per cent zinc (Sample Q923654, Assessment Report 35895). This sample was taken about 150 metres south of Q923652 along the eastern edge of a south to southeast-trending breccia zone.

See Apex (104G 013), Dev 4NW (104G 332), Dev 7410 (104G 333) and Dev 3, (104G 334) for related geological and work history details.