The deposit occurs on Big Interior Mountain at the southern end of the Buttle Lake Uplift. The stratigraphy of the uplift has recently been mapped by Juras (1987) and the nomenclature revised. New revisions have since taken place and the uplift is now described as consisting of the Upper Pennsylvanian to Lower Permian Buttle Lake Group (formerly the upper part of the Sicker Group) and the Devonian to possibly Mississippian or Pennsylvanian Sicker Group (Nick Massey, personal communication, 1990).

The Buttle Lake Group consists of: (1) the Lower Permian (?) Henshaw Formation composed of conglomerate, epiclastic deposits and vitric tuffs; and (2) the Lower Permian to Pennsylvanian Azure Lake Formation (formerly Buttle Lake Formation) consisting of crinoidal limestone and minor chert.

The Sicker Group consists of: (1) the Mississippian or Pennsylvanian(?) Flower Ridge Formation largely comprising coarse mafic pyroclastic deposits; (2) the Lower Mississippian (?) Thelwood Formation, a bedded sequence of siliceous tuffaceous sediments, subaqueous pyroclastic deposits and mafic sills; (3) the Upper Devonian Myra Formation consisting of basaltic to rhyolitic flows and volcaniclastic rocks, lesser epiclastic sediments, argillites and cherts, and massive sulphide mineralization; and (4) the Upper Devonian or older Price Formation comprising feldspar-pyroxene porphyritic andesite flows, flow breccias and minor pyroclastic deposits.

The Myra Formation may be correlative with the McLaughlin Ridge Formation in the Cowichan uplift area; the Price Formation may correlate with the lower part of the McLaughlin Ridge Formation and/or the Nitinat Formation.

The area of the occurrence was originally mapped as Sicker Group rocks with areas of Buttle Lake limestone (Azure Lake Formation) and the stratigraphy has not been further refined to date (Open File 463). The rocks underlying the area consist of cherty volcanics, impure tuffs, and small bodies of intrusive basalt. The contact of a mainly quartz diorite batholith (unofficially the Bedwell River batholith) of the Early to Middle Jurassic Island Plutonic Suite cuts through the area.

Great rusty cliffs of quartz diorite, extending for about 600 metres west and northwest, form the northern wall of a cirque. Slabs of altered andesite or basalt form a veneer on the cliff face locally. A smaller mass of quartz diorite is found nearby due west of the southern boundary of the first. The cliffs contain minute fractures and tiny scattered grains of pyrite, pyrrhotite and some chalcopyrite and malachite. A large chip sample taken over 40 metres contained nil gold and silver and a trace of copper (Bulletin 13). At the 1380 metre elevation level an adit was tunnelled. In front of the portal a dyke of hornblende-feldspar-porphyry, 3 metres wide, strikes 040 degrees, dips 85 degrees northwest and contains pyrrhotite and chalcopyrite in minute fractures. Assays showed nil gold and silver and trace copper from the adit.

Upslope to the west of the cirque at the contact of basalt and limestone an area of skarn mineralization consisting of irregular masses of sulphide from 2 to 50 centimetres exists. These masses consist of chalcopyrite, garnet and some quartz. A selected sample of this material contained 4.8 grams per tonne gold, 102.86 grams per tonne silver and 11.1 per cent copper (Bulletin 13). At some points, notably near the mountain crest, garnet, epidote, amphibole, magnetite, molybdenite, malachite and other silicates replace basalt and limestone. At several points along the batholith-limestone contact rich copper mineralization was observed.

The prospect was discovered in 1899 by Joe Drinkwater. The claims were purchased for $250,000 in 1912 by a small group of investors, chaired by R.R.B. Fielding, the 9th Earl of Denbigh from England. Road building and development continued until 1914, when it stopped due to the war and establishment of Strathcona Provincial Park. Between 1959 and 1964, over 3,200 metres of diamond drilling in 32 holes was completed on this deposit.