The Nani occurrence is underlain by a volcanic and volcanic- sedimentary roof pendant which trends northeast within the southern part of the Jurassic to Tertiary Coast Plutonic Complex. The volcanic rocks strike north to northwest with various dips. The roof pendant rocks include greenstones, agglomerates, tuffs, schists, rhyolitic volcanics, tuffaceous agglomerates, limestone, graphic argillite and mixed sedimentary and volcanic conglomerates. Meta- morphism is variable but northwest trending foliations are common. Local areas are capped by Tertiary basalts. Intrusive rocks of the Coast Plutonic Complex are locally dioritic in composition and lie southeast and north of the area.

In the immediate vicinity of the wokings there are argillites, and sandstone grading to conglomerate. The local strike of the rocks is 150 degrees, dips being approximately vertical. Within highly metamorphosed argillites there is a meandering body of quartz that pinches and swells from several centimetres up to 5 metres in width. The vein has a general strike of 105 degrees and a dip of between 20 and 35 degrees south. The main showing, up to 4.6 metres in width with country rock inclusions, has a southerly dip into the hill of 20 to 30 degrees.

Mineralization is light, consisting of scattered streaks and disseminations of pyrite and chalcopyrite occuring chiefly along the walls or in shattered quartz areas. A selected sample of well min- eralized material assayed 4.11 grams per tonne gold, 123.43 grams per tonne silver and 2.0 per cent copper (O'Grady, 1936).

Plans of the workings drawn up around 1936 show about 260 metres of underground development in two tunnels, with indication of another several hundred feet more of proposed tunnelling. About 13.6 tonnes of ore are reported to have been picked and sacked for shipment (Geological Survey of Canada Summary Report, 1917, Part B).