Northeastern Washington massive sulfide

Region West, Northwest
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Permissive tracts NR17 and NR18 for Massive sulfide, Besshi- and Kuroko-type deposits polygons extracted and merged from the 1995 National Assessment (U.S. Geological Survey National Mineral Resource Assessment Team, 2002).
Identified resources Historical production of zinc.
Production Minor past production for zinc (early 1900s).
Status Past mining.
Estimated resources Unknown.
Geologic maps Joseph (1990a), scale 1:100,000; Stoffel and others (1991), scale 1:250,000.
Geophysical data Inadequate aeromagnetic data; less than 20% of the area covered by rank 2 aeroradiometric data.
Favorable rocks and structures All of the Permian through Jurassic rocks of the Quesnellia terrane are considered permissive for Kuroko-type massive sulfide deposits (Stoffel and others, 1991). The Quesnellia terrane in northeastern Washington consists of Permian through Jurassic arc volcanic rocks and associated sedimentary rocks (Mortimer, 1986). Paleozoic rocks of the Covada Group or Kootenay terrane in northern Washington and southern British Columbia are host to deposits and prospects that have characteristics similar to Besshi-type massive sulfide deposits (U.S. Geological Survey National Mineral Resource Assessment Team, 2002).
Deposits None.
Evidence from mineral occurrences In British Columbia in equivalent rocks, the Goldstream and True Blue deposits have reserves of Cu, Zn, and Ag (U.S. Geological Survey National Mineral Resource Assessment Team, 2002).
Geochemical evidence Holden mine assays: 0.2-0.16% Ni, 0.19% U3O8 equivalent in one sample.
Geophysical evidence Unknown.
Evidence from other sources Unknown.
Comments In British Columbia, two important deposits of this type are known from this belt of rocks. The Goldstream deposit has reserves of 3.2 million metric tons containing 4.5% Cu, 3.1% Zn, and 20 grams/metric ton Ag (Höy, 1991). The True Blue deposit further south is another deposit of this type in British Columbia. In Washington, prospects and small deposits of this type are known but none have been major producers.
Cover thickness and description Unknown.
Authors Allen K. Andersen, Deborah A. Briggs.
New data needs Mapping, geophysics, geochemistry, and structural analysis.
Geologic mapping and modeling needs Less than 25% of focus area has mapping at a scale of 1:24,000. Remainder is covered by intermediate 1:48,000 to 1:62,000 scale mapping.
Geophysical survey and modeling needs Half the study has QL3 aeromagnetic and QL4/5 for remainder. Aeroradiometric at QL2 covers only around a quarter. Need higher resolution aeromagnetic data as aeroradiometric data likely not useful for this deposit type.
Digital elevation data needs Most of the focus area is covered by existing or planned coverage.