The Sil 4 showing is located on the Koksilah River, 8.5 kilometres north west of Mill Bay.

The area is underlain by a section of Mount Mark Formation (Buttle Lake Group) carbonate and interbedded pelitic and tuffaceous rocks intruded by a feldspar hornblende porphyry. Local sulphide- rich shear zones and skarn mineralization is probably related to the intrusion of the "Koksilah" stock of the Early to Middle Jurassic Island Plutonic Suite (formerly called the Island Intrusions).

Along the Koksilah River pods of massive sulphide occur, up to 3 metres in width, consisting of semi-massive to massive pyrite and garnetite plus or minus pyrrhotite, chalcopyrite and magnetite.

In 1983 through 1985, Reward Resources completed programs of prospecting, geochemical sampling and ground geophysical surveys on the Independence, Koksilah, Pacific Star and Western mineral claims. In 1986, Hollycroft and Nexus resources completed a program of geological mapping and rock sampling on the Sil claims. A grab sample of chalcopyrite- bearing vein assayed 4 per cent copper, 30.9 grams per tonne silver and 0.07 grams per tonne gold, while grab samples of massive sulphides yielded values up to 0.485 per cent copper, 22.35 per cent iron and 2.2 grams per tonne silver (Assessment Report 15218).