Unnamed Mines (ARDF - TN078; near junction of Boulder Creek and Little Boulder Creek), Hot Springs Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Unnamed Mines (ARDF - TN078; near junction of Boulder Creek and Little Boulder Creek)	- not defined -
Hot Springs Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: This site represents an area of placer mining on Boulder Creek near its junction with Little Boulder Creek. The site is at a (placer) mine symbol in the northwest quarter of section 30, T. 4 N., R. 17 W., of the Fairbanks Meridian. The location is accurate within several hundred feet. The site corresponds to location 22 of Cobb (1972).
Geology: The Boulder Creek area is underlain by Jurassic or Cretaceous clastic sedimentary rocks, which have been intruded and contact metamorphosed by the Cretaceous monzodiorite to granite Roughtop Mountain pluton (Chapman and others, 1982; Reifenstuhl and others, 1998). Locally, the area is covered by unconsolidated Quaternary deposits (Chapman and others, 1982). Published descriptions of the placer deposits, and of the locations of workings, on Boulder and Little Boulder creeks are ambiguous. The following description herein is assumed to apply to the placer deposits in the area of this site. Mining on Boulder Creek was first reported in 1915 (Brooks, 1916). The creek has an asymmetrical valley (Chapin, 1919); the south side is steep with no gravels, and the north side is flat with alluvium 8 to 12 feet thick. The placer extends for several miles, with a workable width of 1,200 feet. In 1917, over 200,000 feet of bedrock were cleaned (Chapin, 1919). A hydraulic plant was operated in 1931 from May to September, and 7,000 square feet of bedrock was cleaned from a bench of Boulder Creek (Mertie, 1934). Gold 818 fine from this operation reportedly had an assay value of $16.90 per ounce (at $20.67 per ounce). There was relatively consistent small-scale production in the 1930's from Boulder Creek, although the amount of gold recovered was not made public. Early references to Little Boulder Creek reported that the placer ground was thin, with low gold grades (Brooks, 1918). Chapin (1919) reported prospecting the following year in 6 to 12 feet of alluvium consisting of silt with layers and lenses of angular slate fragments. Waters (1934) and Moxham (1954) reported that, in addition to gold, the placer concentrates contained magnetite, ilmenite, zircon, rutile, garnet, sphene, and monazite. In 1949, pan concentrates assayed 0.21 percent equivalent uranium oxide, whose source was speculated to be the pluton at Roughtop Mountain (Moxham, 1954). Moxham also identified chromite float in Boulder Creek, whose source is probably serpentinite on Serpentine Ridge (TN079), south of the creek (Berg and Cobb, 1967). In 1967, two properties on Boulder Creek were being intensely prospected and another property was to be mined in 1968 (Heiner and others, 1968). Farrell & Higgins were also active on Little Boulder Creek in 1967. Boulder Creek Mining Company (Les and Dorthy Fickes) worked a cut on Boulder Creek during 1986 (Bundtzen and others, 1987). In 1992, R. Schroder and Beatrice Schafer both mined on Boulder Creek (Swainbank and others, 1993). Placer Mine Services mined along the creek in 1997 (Swainbank and others, 1998), and Richard Wilder mined in 1998 (Szumigala and Swainbank, 1999). In 1990, J.L. Wood and Vern Petefish worked on Little Boulder Creek. In 1991, Wood continued to work in Little Boulder Creek, while Windy Hill Mining prospected some areas (Bundtzen and others, 1992). Wood also mined on Little Boulder Creek in 1997-98 (Swainbank and others, 1998; Szumigala and Swainbank, 1999).
Workings: The first reports of placer mining on Boulder Creek were in 1915 (Brooks, 1916), and the deposits were worked nearly continuously through the 1930's. There is no public record of the amount of gold recovered during this period. More recently, there has been placer mining on both Boulder and Little Boulder creeks. In 1967, two properties on Boulder Creek were being prospected and another property was to be mined in 1968 (Heiner and others, 1968). Farrell & Higgins were also active on Little Boulder Creek in 1967. Boulder Creek Mining Company (Les and Dorthy Fickes) worked a cut on Boulder Creek during 1986 (Bundtzen and others, 1987). In 1992, R. Schroder and Beatrice Schafer both mined on Boulder Creek (Swainbank and others, 1993). Placer Mine Services mined along the creek in 1997 (Swainbank and others, 1998), and Richard Wilder mined in 1998 (Szumigala and Swainbank, 1999). In 1990, J.L. Wood and Vern Petefish worked on Little Boulder Creek. In 1991, Wood continued to work in Little Boulder Creek, while Windy Hill Mining prospected some areas (Bundtzen and others, 1992). Wood also mined on Little Boulder Creek in 1997-98 (Swainbank and others, 1998; Szumigala and Swainbank, 1999).
Age: Quaternary.

Commodities (Major) - Au; (Minor) - Cr, REE, U
Development Status: Yes; small
Deposit Model: Placer Au (Cox and Singer, 1986; model 39a).

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Link to USGS - Alaska:	TN078

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References