The O.K. (L.348) occurrence is located on the western side of the Sand River, approximately 3 kilometres north- north west of the river mouth and at an elevation of 750 metres.

The area is underlain by east-northeast dipping rocks of the Upper Triassic Vancouver Group consisting of a north trending elongate sequence of Quatsino Formation limestones underlain by Karmutsen Formation volcanics. The limestone is encompassed by the Karmutsen rocks on the south and west and by plutonic rocks of the Early to Middle Eocene Tofino Intrusive Suite (previously Catface Intrusions) on the north and east.

Skarn mineralization is reported to occur in dioritic rock near its contact with limestone. The zone strikes 160 degrees with a dip of 50 degrees and is up to 60 metres long and 3 metres wide. It is characterized by masses of chalcopyrite and associated pyrite, pyrrhotite and magnetite. A 32 metre tunnel had been completed by. A sample taken from the workings assayed 4.7 per cent copper and 27.4 grams per tonne silver (Minister of Mines Annual Report 1918, page 263). Samples taken from the underground workings were reported to grade lower than surface samples.

Another report describes the prospect as consisting of 5 distinct veins about 10 centimetres wide and exposed on the surface for "several hundred feet". Each of the veins are reported to lie alongside a diorite dike also having a width of about 10 centimetres. The rock type in which the dikes and veins occur was not reported. One sample contained 4.3 grams per tonne gold and 15 per cent copper (Unsigned 1910 Report).