Falcon Arm Prospect, Chichagof Mining District (Chicagof Mining District), Sitka, Alaska, USAi

Regional Level Types
Falcon Arm Prospect	Prospect
Chichagof Mining District (Chicagof Mining District)	Mining District
Sitka	City Borough
Alaska	State
USA	Country

The prospect is in West Chichagof-Yakobi Wilderness.
Location: The Falcon Arm prospect is at an elevation of about 180 feet on the valley wall east of the head of Falcon Arm. The prospect is 0.4 mile north-northwest of the center of sec. 10, T. 50 S., R. 59 E. It is location P-90 of Bittenbender and others (1999), location 42 of Cobb (1972, 1978), and MAS no. 0021140033 (U.S. Bureau of Land Management, 2002). The location probably is accurate within 0.2 mile.
Geology: Johnson and Karl (1985) map the rocks in the area of this prospect as Cretaceous graywacke. The rocks are cut by numerous steeply-dipping, mainly northwest-striking faults. They include the extensions of the faults at the Hirst (SI087) and Chichagof (SI093) mines, which control the mineralization there and whose traces are about a mile northeast of this prospect. Reed and Coats (1941) describe the prospect as fault-controlled, auriferous quartz veins up to 4 inches thick in graywacke. The graywacke is cut by numerous, 1- to 3-foot-thick dikes of light-colored, fine-grained, intrusive rock. The graywacke strikes about N50W and dips about 70SW; the principal faults and splits from them strike N35W-N30E and dip steeply west. Some of the dikes are similar in attitude to some of the faults. The principal set of joints strikes N45E and is nearly vertical. Workings include a 2,260-foot crosscut and a 750-foot drift off the crosscut. Bittenbender and others (1999), citing Overbeck (1919) and Still and Weir (1981), report that the Falcon Arm prospect was staked in 1916 on fault-controlled, auriferous quartz veins in mafic dikes and graywacke. Workings consist of 4 adits totaling 3,130 feet, and a pit . The most significant mineralized rock is quartz rubblecrop; blocks of it up to 1.2 feet thick assayed 0.5 ounce to 2.15 ounces of gold per ton. A sample from the upper workings contained 2.16 ounces of gold per ton. There are no published records of production but the assay values and the extent of the workings indicate that some gold may have been produced. Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler, 1995; Goldfarb, 1997; Goldfarb and others, 1997).
Workings: Reed and Coats (1941) report a 2,260-foot crosscut and a 750-foot drift off the crosscut. Bittenbender and others (1999) report that the Falcon Arm prospect was staked in 1916 and developed by 4 adits totaling 3,130 feet and a pit.
Age: Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler and others, 1995; Goldfarb, 1997; Goldfarb and others, 1997).
Production: There are no published records of production but the assay values and the extent of the workings indicate that some gold may have been produced.

Commodities (Major) - Au
Development Status: Undetermined.
Deposit Model: Low-sulfide gold-quartz veins (Cox and Singer, 1986; model 36a).

Other Databases

Link to USGS - Alaska:	SI127

Other Regions, Features and Areas containing this locality

References