The country rocks in the area of this site include: pelitic metasedimentary and subordinate andesitic metavolcanic strata of the Jurassic or Triassic Hazelton Group; recrystallized granodiorite of the Triassic Texas Creek Granodiorite, which intrudes the Hazelton rocks; quartz monzonite and granodiorite of the Hyder Quartz Monzonite batholith, which intrudes the Hazelton and Texas Creek rocks; and Tertiary lamprophyre dikes, which intrude all of the foregoing rock units (Buddington, 1929; Smith, 1973, l977; Berg and others, 1988).

The deposits consist of quartz fissure veins in (Texas Creek) granodiorite and Hazelton metasedimentary rocks (Buddington, 1929, p. 63-67; West and Benson, 1955, p. 31-45; Byers and Sainsbury, 1956, p. 137-138; Cobb and Elliott, 1980, p. 78). The Texas Creek-Hazelton contact is a north-trending, high-angle fault that runs through the middle of the property; the Hazelton lays east of the fault. The veins locally are cut by dikes of aplite and granodiorite porphyry or pegmatite that probably are apophyses of the Hyder Quartz Monzonite batholith, and by lamprophyre dikes. The veins range in thickness from an inch or so to as much as 8 feet, and have been traced in surface or underground exposures for as much as 475 feet. The veins contain sulfide minerals, occasionally in massive shoots up to several inches thick, that mainly include pyrite, pyrrhotite, chalcopyrite, galena, sphalerite, and minor tetrahedrite and freibergite. Free gold and native silver have been reported, as have secondary oxides of the copper, lead, silver, and iron sulfides. A secondary, radioactive mineral, tentatively identified as uranium sulfate, occurs as a thin, yellowish coating on some of the sulfide and oxide minerals and on fracture surfaces; the primary radioactive mineral, which appears to be associated with rutile, has not been identified (West and Benson, 1955, p. 41). The Fish Creek no. 2, or Gray Copper, vein contains scheelite and barite in addition to the sulfides. Molybdenite flakes occur in some of the aplite and pegmatite dikes.

On the basis of lead-isotope studies, Maas and others (1995, p. 254) established that the age of the Gray Copper vein is Eocene, and suggest that the Ruby Silver vein also is Eocene. The veins thus are roughly contemporaneous with the emplacement of the Hyder Quartz Monzonite batholith.