California; Connolly and Jensen Mine (or Jannsen), Nome Mining District, Nome Census Area, Alaska, USAi

Regional Level Types
California; Connolly and Jensen Mine (or Jannsen)	Mine
Nome Mining District	Mining District
Nome Census Area	Census Area
Alaska	State
USA	Country

Complex target within major shear zone.
Location: The California mine is in the headwaters of Goldbottom Creek. The main workings are in and near a west-flowing unnamed tributary at the end of the jeep trail at the north end of the Snake River road. This tributary was called Henry Gulch by Cathcart (1922, p. 253). The mine is on the boundary between section 25, T. 8 S., R. 34 W., and section 30, T. 8 S., R. 33 W., Kateel River Meridian. The mine is located within about 500 feet of the coordinates. It is locality 3 of Hummel (1962 [MF 248]) and locality 22 of Cobb (1972 [MF 46], 1978 [OFR 78-93]).
Geology: The California vein was discovered and developed before 1908 (Smith, 1908; Chapin, 1914 [B 592-L, p. 397-407]; Mertie, 1918 [B 451-458]). It is localized in a subsidiary shear zone to a north- to northeast-striking regional fault. The lode is exposed in shallow cuts in a west-draining side canyon to upper Goldbottom Creek. It consists of contorted, sheared, and slickensided schist and quartz masses as much as 3 feet across in a zone that strikes about N 10 W and dips 80 to 85 degrees east. The quartz masses reportedly assayed as much as about 2.5 ounces of gold per ton, but only about 0.4 or 0.5 ounce of gold per ton were recovered by processing. Mr. Jensen, an owner at one time, retained specimens from the California lode of very rich gold ore (Pearse Walsh, oral communication, 1995). Small amounts of pyrite, arsenopyrite, and stibnite accompany the gold, and some molybdenun and tungsten values have been reported (Mertie, 1918 [B 662-I, p. 451-458]; Wedow and others, 1952, p. 35). Higher grade ore may be confined to lenticular ladder zones within the major shear zone. The California lode was developed by a 70-foot decline that was reported to be in vein material to a depth of 33 feet. The ore was processed by a jaw crusher and stamp mill that may not have crushed ore fine enough to liberate all the gold. Some development was reported in 1932; in 1938 about 100 feet of drift was driven, and some ore was milled (Smith, 1934 [B 857-A]; 1939). Kennecott Exploration Company explored the property with trenches and three diamond drill holes in 1995 and found mineralized rocks with low gold grades. The structure that localizes the California lode is subsidiary to a regional fault that strikes north- to north-northeast and can be traced southerly to at least Bangor Creek. The regional fault zone is hundreds of feet wide, and rock within the zone is highly contorted, graphitic mica schist (C.C. Hawley, written communication, 1995). The fault probably continues to the north-northeast into lower Fred Creek and the Stewart River valley, where it is covered by alluvium. South-southwest of the California lode, massive quartz boulders as much as several feet across occur as surface float along the fault as far as Goldbottom Creek. In addition, highly graphitic quartz veins, which resemble the main lode, occur in an east-draining side canyon to Goldbottom Creek about 1,200 feet southwest of the main California incline. At this point, the main, north- to north-northeast-trending shear zone is about 1,000 feet across. Gold-bearing veins, such as the California lode, are possibly ladder structures within the main shear zone. Hummel (1962 [MF 248]), Sainsbury, Hummel, and Hudson (1972), and Bundtzen and others (1994) mapped the major Penny River fault of north-east strike about one-half mile west of the California lode. On the basis of mapping by one of the compiler's (C.C. Hawley), the fault exposed at the California lode is a major branch of the Penny River fault,or it is the main Penny River fault and the fault mapped by others is a subsidiary structure. About 250 feet east of the main California decline, non-contorted quartz-mica schist is overlain by the main marble unit of the Mount Distin area. This is the massive marble unit of Bundtzen and others (1994); it may have a Paleozoic protolith, but most of the metasedimentary rocks in this area are part of the Nome Group derived from Proterozoic to early Paleozoic protoliths (Till and Dumoulin, 1994). At this location, the marble is folded into an open, north-trending syncline at a high angle to the main, east-west Mount Distin syncline. The Nome Group underwent regional blueschist facies metamorphism in the Late Jurassic or Early Cretaceous (Sainsbury, Coleman and Kachadoorian, 1970; Forbes and others, 1984; Thurston, 1985; Armstrong and others, 1986; Hannula and McWilliams, 1995). The blueschist facies rocks were recrystallized to greenschist facies or higher metamorphic grades in conjunction with regional extension, crustal melting, and magmatism in the mid-Cretaceous (Hudson and Arth, 1983; Miller and Hudson, 1991; Miller and others, 1992; Dumitru and others, 1995; Hannula and others, 1995; Hudson, 1994; Amato and others, 1994; Amato and Wright, 1997, 1998). Lode gold mineralization on Seward Peninsula is mostly related to the higher temperature metamorphism in the mid-Cretaceous (Apodoca, 1994; Ford, 1993 [thesis]; Ford and Snee, 1996; Goldfarb and others, 1997).
Workings: The California lode was developed by a 70-foot decline that was reported to be in vein material to a depth of 33 feet. There are shallow pits, including a pit on the marble-schist contact about 250 feet east of the California incline. This pit has abundant bluish quartz. Another pit is about 1,200 feet southwest of the incline in a side canyon on the west side of Goldbottom Creek. The ore was processed by a jaw crusher and stamp mill that may not have crushed ore fine enough to liberate all the gold. Some development was reported in 1932; in 1938 about 100 feet of drift was driven and some ore was milled (Smith, 1934 [B 857-A], 1939 [B 917-A]). Kennecott Exploration Company explored the property with trenches and three diamond drill holes in 1995 and found mineralized rocks with low gold grades.
Age: Mid-Cretaceous?; structures controlling deposits post-date regional metamorphism - mineralization could be similar in age to other lode gold deposits of Seward Peninsula.
Alteration: Extensive iron-staining of the host schist reflects oxidized pyrite or arsenopyrite.
Production: Small production in early 1900's, also some probably about 1937-38.

Commodities (Major) - Au; (Minor) - Ag, Mo, Sb, W
Development Status: Yes; small
Deposit Model: Low sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).

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Link to USGS - Alaska:	NM062

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References