The Porto Rico (L.2385) occurrence is located on Barrett Creek, 15.5 Kilometres north-northwest of Salmo. Underground development began in 1896 and production is recorded for 1897.

The area is underlain by basaltic to andesitic lapilli tuff and pyroclastics (Unit Je3) of the Lower Jurassic Elise Formation, Rossland Group (Open File 1989-11). These are intruded by the Late to Middle (?) Jurassic Mammoth Intrusions comprising plagioclase augite porphyritic diorite (?).

The occurrence consists of a quartz-filled fissure that strikes northeast and dips about 45 degrees to the northwest. The host rock is comprised of an augite porphyry sill which intrudes andesitic volcanics. The quartz vein averages about 0.8 metre in width and hosts pyrite, gold, arsenopyrite and very minor galena, sphalerite and chalcopyrite.

In 1899, 3719 tonnes of ore was mined producing 108,083 grams of gold and 31,103 grams of silver. Production from the Porto Rico vein over 13 years, in the period 1897 to 1969, totalled 5740 tonnes which produced 178,470 grams gold, 46,405 grams silver, 138 kilograms lead, 51 kilograms zinc and 322 kilograms copper.

In 1979, mineralization was observed on the Sunshine (Lot 2389) claim. It occurs in an old shaft and consists of a 1.3-metre wide shear zone which strikes east-west and dips 55 degrees north. Pyrite and arsenopyrite occur in a breccia zone that is 0.5 metre wide. The sulphides cement irregular fragments of quartz and altered andesitic wallrock. The shear cuts porphyritic augite andesite which is stratigraphically below the augite porphyry sill in which the main vein on the Porto Rico claim is exposed. The andesitic volcanics show extensive propylitic alteration. Samples assayed 11.65 to 24.34 grams per tonne gold and 3.42 to 3.77 grams per tonne silver (Assessment Report 7702).

Northeast of the main vein, on the Lizzie B (Lot 2386) claim, malachite staining was found in mafic dyke material.