By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
The only gold deposits in Kittitas County that have yielded 10,000 ounces or more are those of the Swauk district. In the early days the Peshastin district, now part of Chelan County (p. 256), was included in Kittitas County and accounted for much of its early production. Recorded county production from 1903 through 1959, all of which was attributed to the Swauk district, was 7,141 ounces, of which 4,972 ounces was placer gold. Production before 1903 is unrecorded, but there is an 11-year record from 1884 to 1895 (Smith, 1903, p. 76) which credited the county with $764,163 worth of gold (37,095 ounces).
Landes, Thyng, Lyon, and Roberts (1902, p. 88-89), referring to the early production of the Swauk placers, stated, "It is not possible to form even an estimate of the total output of these placers. The early workers did not keep any accurate record of their output, and the present operators are keeping their information to themselves."
The Swauk district is between lat 47°14' and 47°16' N. and long 120°28' and 120°42' W.
Placers were discovered in this area in 1868 and auriferous veins, in 1881 (Smith, 1903, p. 76). Most of the placers contain fine gold, but some deposits are characterized by coarse nuggets and wire and leaf gold. The limited area of the drainage basin and the lack of rounding of the gold particles make it seem likely that the gold was derived from the quartz veins in the vicinity.
The vein deposits are narrow fissure veins in sandstone and shale of the Swauk Formation of Eocene age. A peculiar type of breccia known as birds-eye quartz constitutes much of the vein material in several mines (Smith, 1903, p. 79-80). This consists of fragments of black shale enclosed in quartz and calcite. Gold occurs in fine grains in the quartz and as incrustations on the surface of quartz.
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