Lost Lucy

Prospect, Inactive

Commodities and mineralogy

Main commodities Au
Ore minerals pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale JU
Quadrangle map, 1:63,360-scale B-2
Latitude 58.2917
Longitude -134.4304
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Lost Lucy prospect is at an elevation of approximately 300 feet, on northeast Douglas Island. It is 1.2 miles northwest of Douglas, 1/2 mile southeast of Kowee Creek, and 1 mile northwest of Lawson Creek, in the NE1/4NE1/4 section 27, T. 41 S., R. 67 E. of the Copper River Meridian. The location is accurate.

Geologic setting

Geologic description

The Lost Lucy prospect was discovered before 1939 and has a 315-foot adit with a raise to the surface. The adit is currently (2001) shut with a metal plate and concrete because it is in a housing development. The deposit consists of quartz stringers and 1- to 2-foot quartz veins in slate and greenstone. The veins contain pyrite and low gold values (Redman and others, 1989; Wells and others, 1986). The rocks in the general area are Upper Jurassic or Cretaceous marine argillite and graywacke, interbedded with andesite or basalt (Brew and Ford, 1985). The bedded rocks are regionally metamorphosed to prehnite-pumpellyite or greenschist grade, and cut by diorite or gabbro dikes and sills.
This prospect is in the Juneau Gold Belt, which consists of more than 200 gold-quartz-vein deposits that have produced nearly 7 million ounces of gold. These gold-bearing mesothermal quartz vein systems form a zone 160 km long by 5 to 8 km wide along the western margin of the Coast Mountains. The vein systems are in or near shear zones adjacent to west-verging, mid-Cretaceous thrust faults. The veins are hosted by diverse, variably metamorphosed, sedimentary, volcanic, and intrusive rocks. From the Coast Mountains batholith westward, the host rocks include mixed metasedimentary and metavolcanic sequences of Carboniferous and older, Permian and Triassic, and Jurassic-Cretaceous age. The sequences are juxtaposed along mid-Cretaceous thrust faults (Miller and others, 1994). The sequences are intruded by mid-Cretaceous to middle Eocene plutons, mainly diorite, tonalite, granodiorite, quartz monzonite, and granite. Sheetlike tonalite plutons emplaced just east of the Juneau Gold Belt and undeformed granite and granodiorite bodies that are emplaced farther to the east are between 55 and 48 Ma (Gehrels and others, 1991). The structural grain of the belt is defined by northwest-striking, moderately to steeply northeast-dipping, penetrative foliation that developed between Cretaceous and Eocene time (Miller and others, 1994). The majority of the veins in the Juneau Gold Belt strike northwest. Isotopic dates indicate that the auriferous veins in the Juneau Gold Belt formed between 56 and 55 Ma (Miller and others, 1994; Goldfarb and others, 1997).
Geologic map unit (-134.432171462549, 58.2913721493919)
Age of mineralization Isotopic dates indicate that the auriferous veins in the Juneau Gold Belt formed between 56 and 55 Ma (Miller and others, 1994; Goldfarb and others, 1997).

Production and reserves

Workings or exploration The Lost Lucy prospect was discovered before 1939, and has a 315-foot adit with a raise to the surface.
Indication of production None

References