Shasta County California Gold Production
The West Shasta copper-zinc district, 20 miles northwest of Redding, originally was a gold district, but it later became one of the chief copper producers in the State. Prospectors, drawn to Shasta County by the placer discoveries on Clear Creek in 1848, soon found gold placers in the area west of Redding (Kinkel and others, 1956, p. 76). Copper deposits were also noted at this time, but interest was centered on the gold. In 1879 considerable excitement was aroused by the discovery of silver in the gossan at the Iron Mountain property in the southern part of the district. Later, in the search for precious metals, large quantities of copper sulfides were found beneath the gossan. In the early 1900's copper was mined on a large scale from the Iron Mountain and Balaklala mines, and gold and silver were obtained as byproducts. Small bodies of high-grade zinc ore were mined at the Mammoth and Iron Mountain mines. After 1919, production declined, and by 1953 gold was no longer listed in the annual production data for the district. Total gold production through 1959 was about 520,000 ounces.
The oldest rocks of the West Shasta copper-zinc district are basic lava flows, breccias, and tuffs that characterize the Copley Greenstone of Early (?) Devonian age. This is overlain by the Balaklala Rhyolite of Middle Devonian age, and the Balaklala is overlain by the Kennett Formation, which is composed of black cherty shale, tuff, and limestone of Middle Devonian age. Shale, sandstone, and conglomerate of the Bragdon Formation of Mississippian age rests on the Kennett Formation. In Jurassic time the Paleozoic rocks were invaded first by the Mule Mountain albite granite stock and then by the Shasta Bally biotite-quartz diorite batholith. Deformation accompanied the intrusions, and the Paleozoic formations were folded into a broad anticlinorium. Numerous faults dislocate parts of the arch. In the southern part of the district, elastics of the Chico Formation of Late Cretaceous age and of the Red Bluff Formation of Pleistocene age unconformably overlie the Copley Greenstone (Kinkel and others, 1956, p. 8-9).
The ore deposits, which were emplaced during Late Jurassic or Early Cretaceous time, consist of massive base-metal sulfide replacement bodies in the Balaklala Rhyolite. The ore minerals are pyrite, chalcopyrite, and sphalerite, and small amounts of magnetite, galena, tetrahedrite, pyrrhotite, gold, and silver. The ore controls are believed to be a combination of the anticlinorium structure, favorable lithologic features of the Balaklala Rhyolite, and fissures, which provided access for solutions (Kinkel and others, 1956, p. 79-100).
WHISKEYTOWN DISTRICT
The Whiskeytown district is along Clear Creek about 5 miles southeast of French Gulch.
The mines are along the edge of a mass of alaskite porphyry of Jurassic or Cretaceous age that cuts the Copley Greenstone of Early (?) Devonian age and lies adjacent to a large mass of quartz diorite and granodiorite of Jurassic or Cretaceous age (Ferguson, 1914, p. 47). The Bragdon Formation, of Mississippian age, is exposed in the northern part of the district.
The Mad Mule mine, which has been the largest producer of the district, is in a diorite porphyry dike that cuts the Bragdon Formation. The ore bodies are small lenses of calcite that occur at irregularities along the contact between the dike and sedimentary rock. Gold occurs most commonly as a thin film on calcite at its junction with the enclosing slate. Gold also is found within the calcite masses along cleavage planes. Pyrite and manganese-bearing quartz stringers are minor constituents of the calcite lenses (Ferguson, 1914, p. 52-54). Other ore deposits in the district are in quartz veins with minor calcite and with pyrite as the principal sulfide. Gold occurs free in the quartz and in the pyrite.
Production through 1911 was 63,300 ounces ($1,365,000) of gold (Ferguson, 1914, p. 47-55). The district has been inactive for many years.