By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
The first mineral discoveries in Stevens County were made in 1883 in the Colville district (Weaver, 1920, p. 134). Shortly afterward additional discoveries were made in the Deer Trail and Chewelah districts. A major factor in attracting prospectors to this part of the State was the opening of the Colville Indian Reservation to mineral exploration in 1896.
Rich gold ores were soon discovered on the reservation and across the Columbia River in adjacent parts of Stevens County. Those in Stevens County were quickly mined out, and gold mining in the county virtually ceased in the following years. Subsequent gold production was obtained almost entirely as a byproduct from the mining of base-metal ores.
Total gold production from 1902 through 1959 was 52,145 ounces, mostly from lode mines.
The major gold-producing district in the county is the Orient. The Chewelah district is second in importance, but its total recorded production, byproduct gold from copper-silver ores, is slightly less than 5,000 ounces. Much of Stevens County is underlain by metamorphosed sedimentary rocks of unknown age (Weaver, 1920, p. 44). Locally, these have been intruded by masses of granite and diorite and they are overlain by tuffs, flows, and volcanic breccias with interbedded sediments.
Long irregular tongues of basalt flows of probable Tertiary age overlie the metamorphic and igneous rocks in the southern part of the county where they fill depressions on an earlier Tertiary erosion surface. A few small patches of tuffs, breccias, and lavas of late Tertiary age occur in the west-central and north-central parts of the county.
The Orient (Pierre Lake) district is in northwest Stevens County between lat 48°50' and 48Â°57' N. and long 118°05' and 118°10' W.
This district was formed in 1902 as a result of significant discoveries at the First Thought and Napoleon mines (Fulkerson and Kingston, 1958, p. 4). The First Thought was the major gold producer in the county during 1900-20 (Fulkerson and Kingston, 1958, p. 1).
Recorded gold production for the district through 1942 was 45,057 ounces; all was presumably from lode mines. From 1942, when the First Thought mine was closed, through 1959 no production was reported from the district.
The predominant rocks exposed in the district are andesite and latite flows of the Rossland Formation of Mesozoic or Tertiary age (Weaver, 1920, p. 257-258). These flows overlie various older rocks - shale, limestone, quartzite, and schist, which are typical of the metasedimentary Stevens Series of Weaver (1920, p. 50-51).
Ore deposits occur in the latite in fractured and brecciated zones that are cemented by silica and carbonate. Gold is the chief ore mineral and occurs with finely disseminated pyrite. Bancroft (1914, p. 69) believed that the ore deposits were related to bodies of rhyolite and monzonite porphyry that were emplaced during Mesozoic or Tertiary time.