The Richardson area is characterized by gentle slopes and broad alluvium filled valleys (Prindle and Katz, 1913, p. 140). The area is unglaciated and largely overlain by windblown silt, sand, and loess, locally up to 50 meters thick (Foster and others, 1979). The bedrock in the region comprises greenschist to amphibolite facies schist, marble, and gneiss that have been intruded by various igneous bodies (Bundtzen and Reger, 1977, p. 29). The schist and marble are probably Paleozoic, and the gneiss has a probable protolith of Precambrian and Paleozoic sedimentary and igneous rocks (Weber and others, 1978). The intrusive bodies in the area range in composition from rhyolite to andesite. Fine-grained rhyolite containing quartz and feldspar phenocrysts is common throughout the area (Olson and others, 1985). At the nearby Democrat Lode (BD014), the rhyolite contains arsenopyrite, gold, and pyrite, and is albitic, clay, and sericite altered (R.J. Newberry, oral communication, 1998). Structurally, the Richardson region is cut by a northwest-trending fracture system termed the Richardson Lineament. The lineament appears to correspond with the distribution of the rhyolite and other intrusive bodies and placer gold deposits (Bundtzen and Reger, 1977, p. 29). Also, the lineament tends to separate gneissic rocks to the northeast from schistose rocks to the southwest (Swainbank and others, 1984).
The placer gold fineness mined from Banner Creek ranged from 639.5 to 785 (Menzie and Foster, 1979). Metz and Hawkins (1981) reported the average gold fineness to be 737. Glover (1950) reported a range in gold fineness of 738 to 798 for Banner Creek. Placer and churn-drill hole concentrates contain actinolite, arsenopyrite, biotite, cassiterite, chalcopyrite, dolomite, epidote, feldspar, fluorapatite, galena, garnet, gold, hornblende, ilmenite, magnetite, monazite, muscovite, quartz, pyrite, pyroxene, rutile, scheelite, sphene, stibnite, tourmaline, and zircon (Bundtzen and Reger, 1977). Mining along Banner Creek has included open-cut and drifting methods (Ellsworth and Parker, 1911). In the Banner Creek drainage, schist and gneiss in contact with the rhyolite dikes is hydrothermally altered (Swainbank and others, 1984).Placer gold was first discovered in the Richardson district in 1905. Mining initially occurred on the nearby Tenderfoot Creek (BD039) and expanded to Banner Creek and associated tributaries soon after. Following peak gold production in 1908, mining in the area declined (Olson and others, 1985). From 1905 through 1921, gold production for the Richardson district was approximately 95,000 ounces of gold and 24,000 ounces of silver (Bundtzen and Reger, 1977). Since 1980, mining in the district has produced an additional 10,000 ounces of gold (Olson and others, 1985). Gold production for individual mines and sections of Banner Creek and its tributaries has not been reported separately.