By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Josephine County has been one of the leading producers of gold in Oregon and has yielded significant amounts of the State's chrome and copper output. Gold was found on Josephine Creek as early as 1852, and the following year additional discoveries on Althouse Creek precipitated a rush during which prospectors spread throughout southwestern Oregon. Hydraulic methods were introduced as early as 1856 to mine the placers.
As in many other mining camps, the depletion of the placers in Josephine County led to the search for lode deposits. By the early 1860's quartz mines were active in the Grants Pass district, and somewhat later, in the Galice, Greenback, and Waldo districts.
Diller (1914b, p. 47) estimated that from 1852 to 1900 the annual production of gold in the county exceeded $450,000, or a total of about $21,600,000 (about 1,048,000 ounces) for those years. From 1901 through 1959 the county produced 187,913 ounces of gold. Total gold production from 1852 through 1959, including Diller's estimate, was about 1,235,000 ounces.
The geology of Josephine County is summarized by R. C. Treasher (in Oregon Department of Geology and Mineral Industries, 1942, p. 11-15). The oldest rock is greenstone of Triassic (?) age which underlies much of the southern part of the county, extends north-northeastward, and crops out in the northeast corner. Quartz veins containing iron, copper, zinc sulfides, and gold are common in this rock. The western part of the county is underlain by interbedded sedimentary and volcanic rocks of Jurassic age that strike parallel to the Triassic greenstone. The sedimentary rocks, the Galice and Dothan Formations, are predominantly black slates that contain varying amounts of sandstone, conglomerate, and tuff. Interbedded with these two formations is a greenstone unit. Peridotite and serpentine occupy belts several miles wide within the Jurassic sequence and strike concordantly with the regional north-northeast trend. Sulfide and gold-bearing quartz veins fill fractures in the Jurassic sediments and greenstone.
Masses of igneous rock of Jurassic or Cretaceous age that range in composition from granite to diorite are exposed in the southeast, northeast, and northwest parts of the county. A small patch of Horsetown(?) Formation, of Cretaceous age, is exposed in the Takilma area in the southwest part of the county. At numerous localities throughout the county, channels, which were eroded into rocks of Cretaceous age and older, were filled with gold-bearing conglomerates of Tertiary age (Shenon, 1933b, p. 152-154). Gold placers also occur in high terraces of Pleistocene age along the Rogue River.
The major gold-producing districts in Josephine County are the Galice, Grants Pass, Greenback, Illinois River, Lower Applegate, and Waldo.
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