A Pioneer-drive tramline 4,000 feet long was erected at 800 feet elevation to connect to the lower mine adit, No. 3 tunnel, at 2,955 feet elevation. A new bunkhouse for 16 men was built and underground Zero-level was advanced 55 feet. In 1947 the company continued Zero-level a few feet, started a raise, and diamond drilled the No. 2 shear.

Control of Big Four was taken over by Cassiar Consolidated Mines Limited in 1952 and with the exception of occasional sampling, trail-cutting, and other visits the property has remained inactive.

Production from the Silverado veins is listed at 154 tons from which a few ounces of gold, 31,137 ounces of silver, and some copper, lead, and zinc have been recovered.

Most of this was from pits, trenches, and the development headings on vein mineralization, and only one very small stope was attempted.

Work by the Premier and later companies proceeded on the surmise that the Silverado shear system could be traced southeasterly to join the Prosperity and Porter Idaho systems found on the Marmot River slope of Mount Rainey, a distance of about 1 mile.

Unfortunately, most of the intervening ground is covered by ice and perpetual snow and the high elevation leaves only a very short season for work.

Country rocks in the Silverado area are crudely bedded, green Hazelton volcanic breccias, conglomerates, sandstones, crystal tuffs, and equivalent quartz-chlorite schists, mylonites, and cataclasites.

The epiclastic sequence can be readily seen on the open slopes beneath the ice cap and above the dense vegetation of the lower slopes. The rocks form a minor re-entrant along the contact of the Hyder quartz monzonite which at this locality shows a transgressive compositional change from biotite quartz monzonite in the Barney Gulch section southward through biotite granodiorite at Portland Creek to homblende granodiorite opposite Eagle Point. The homblende-rich phase is best displayed in the
Marmot River section as a border manifestation of the pluton.

In the Silverado Creek contact area the dominantly green country rocks have been indurated and have a mottled, purplish cast which is accentuated in irregular, chlorite schist zones.

Toward Barney Gulch these thin schist lenses assume a more recognizable mylonitic appearance. Major northwesterly and northerly trending chlorite schist zones, which post-date local cataclasis.

All the rocks are cut by the northwest-trending homblende diorite (lampro-phyre) dyke swarms as well as other granitic dykes which include feldspar syenite porphyry near the south end of the ridge at 4,000 feet elevation and several feldspar granodiorite porphyry dykes exposed in gullies below the main mine area.