The Shamrock (Ophir) showing is apparently located on Copper Creek near the "north" shore of Powell Lake about 5 to 8 kilometres from the lakes outlet. The area is underlain primarily by quartz diorite of the Jurassic to Tertiary Coast Plutonic Complex (Geological Survey of Canada Map 1386A).

The showings consist of a series of quartz veins hosting pyrite and lesser amounts of galena, sphalerite, and chalcopyrite. The veins strike in a northeast direction and dip very flatly to the southwest within sheared and fissured diorite.

Reports of vein widths vary. One prominent fissure reportedly shows a maximum width of about six metres, filled with mineralized quartz and breccia. Other reports indicate a maximum vein width of one metre.

Some development work was done on these showings during the early part of the century. At least one tunnel measuring eight metres in length was driven on a one metre quartz vein.

One open-cut exposed lenses of solid ore several centimetres wide in quartz gangue. A sample of this assayed 2.74 grams per tonne gold and 51.43 grams per tonne silver (Minister of Mines Annual Report 1924).