The Aetna claim (Lot 978) is on the south part of the Phoenix pit (082ESE020), immediately south of the Victoria claim (082ESE023) and east of the Knob Hill claim (082ESE020). The Old Ironsides (082ESE021) lies to the northwest. The Aetna was Crown granted to C.E. Galt in 1898. Production is included with the Phoenix.

Systematic development, consisting of an extensive system of tunnels and stopes, began in 1895 and comprised three adit levels on the Old Ironsides and Knob Hill claims. To the east, five levels, serviced in part by the Victoria shaft, were developed on the Victoria and Aetna claims.

The area is underlain by chert, cherty argillite, greenstone and a minor amount of limestone of the Upper Paleozoic Knob Hill Group. These rocks are unconformably overlain by limestone, sharpstone conglomerate, argillite and Eholt volcanics of the Triassic Brooklyn Group. Copper ore occurs in mineralized areas of the Brooklyn limestone, which have all the characteristics of metasomatic replacements. These replacements are composed essentially of chlorite-epidote skarn rocks with variable amounts of garnet, calcite and quartz, accompanied by blebs and disseminations of pyrite, chalcopyrite, magnetite and specularite.

The main ore body outcrops on the Old Ironsides and Knob Hill claims; in its downward and eastward extension it passes into the Victoria and Aetna claims. See Phoenix for additional details on development, geology and mineralization.