Valentine; Falls and Diana; Thomas Prospects, Juneau Mining District, Juneau, Alaska, USAi

Regional Level Types
Valentine; Falls and Diana; Thomas Prospects	Group of Prospects
Juneau Mining District	Mining District
Juneau	City Borough
Alaska	State
USA	Country

Location: This prospect is at an elevation of about 550 feet, in the Johnson Creek drainage near the confluence of Snowslide Gulch. It is 2 miles northwest of Berners Bay and 1/3 mile southeast of the Jualin Mine (JU044) in the NE1/4 section 15, T. 35 S., R. 62 E. of the Copper River Meridian. The location is accurate and marks the center of several workings associated with these prospects.
Geology: There are several prospects at this site. The prospect area is completely covered by colluvium. The prospect area is underlain mainly by sheared and altered Jualin Diorite (Barnett and others, 1988). Workings at the Thomas prospect include a caved adit (Barnett and others, 1988). A sample of dump material contained 0.1 ppm gold (Redman and others, 1989). The Valentine prospect, located on the Falls and Diana claims, is 300 feet west of the Thomas prospect. Workings there include 2 water-filled shafts and a 115-foot adit. The shafts were sunk into felsic (quartz-sericite) phyllite and chlorite phyllite near the contact with the Jualin Diorite. The adit exposes pyritic, quartz-chlorite phyllite. The phyllite hosts a 5-foot band of stratiform pyrite and chalcopyrite which has been traced 150 feet to the southeast. The band contains up to 15% chalcopyrite and is in a shear zone in phyllite near the contact with Jualin Diorite (Redman and others, 1989). U.S. Bureau of Mines samples contained up to 161.9 ppm gold, 89.1 ppm silver, and 5.1% copper (Redman and others, 1989). The Thomas and Valentine prospects are in the Jualin mine area (see JU044), currently (2001) controlled by Coeur Alaska. They are in the Berners Bay district at the north end of the Juneau Gold Belt. The district is characterized by a series of structurally-controlled, mesothermal, gold-bearing quartz veins. Most of the veins are in Early Cretaceous (105 Ma) Jualin Diorite, which intrudes Mesozoic (Upper Triassic) metabasalt. There are both extensional and shear veins that generally strike north to northwest and dip east. Discrete vein systems are defined by one or more through-going quartz veins, many of which are in shear zones (Miller and others, 1995). Hydrothermal muscovite from veins in the Jualin mine are 53.2 Ma to 55.5 Ma (Miller and others, 1994). This coincides with the 55 Ma age of the other mesothermal gold veins in the Juneau Gold Belt (Goldfarb and others, 1997).
Workings: The Thomas prospect include a caved adit. The Valentine prospect, located on the Falls and Diana claims, is 300 feet west of the Thomas prospect and its workings include 2 water-filled shafts and a 115-foot adit. The prospects are currently (2001) under the control of Coeur Alaska.
Age: Hydrothermal muscovite from veins in the Jualin mine are 53.2 Ma to 55.5 Ma (Miller and others, 1994). This coincides with the 55 Ma age of the other mesothermal gold veins in the Juneau Gold Belt (Goldfarb and others, 1997).
Alteration: Sericitic and chloritic.

Commodities (Major) - Ag, Au, Cu, Pb, Zn
Development Status: None
Deposit Model: Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a)

Other Databases

Link to USGS - Alaska:	JU046

Other Regions, Features and Areas containing this locality

References