Tsirku Silver

Occurrences, Probably inactive

Commodities and mineralogy

Main commodities Ag; Cu; Pb; Zn
Other commodities Au
Ore minerals galena; pyrite; malachite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SK
Quadrangle map, 1:63,360-scale B-3
Latitude 59.32
Longitude -136.05
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is centered at an elevation of 3,800 feet about 1.1 mile east of the Tsirku River and 4.0 miles, N59W from the summit of Chunekukleik Mountain. It is in the approximate center of a northwest- trending elongate area with several occurrences of ore minerals that is about 1/2 mile long and 1/4 mile wide. This area is shown as number 25 on sheet of Still and others (1991).

Geologic setting

Geologic description

Still and others (1991) informally named this occurrence 'Tsirku Silver'. They describe it as, '...scattered, narrow, discontinuous silver-bearing zinc-galena-quartz veins hosted in dolomite and limy slate.' A representative chip sample of the highest grade vein contained 0.48 ppm gold, 653.5 ppm silver, 18.4% zinc, and 6.2% copper. According to Gilbert and others (1987), the veins occur within a 6-square-mile area immediately east of the Tsirku River that is cut by a swarm of felsic, intermediate, and mafic dikes. The dikes are probably Tertiary in age, based on a 29.3 + 1 to 33.0 + 1 m.y. age of nearby quartz diorite and granodiorite bodies (MacKevett and others, 1974). The probable Devonian or Mississippian age of the host rocks (Gilbert and others, 1987) establishes a maximum age for the veins. More likely, the veins are the same inferred Tertiary age as the dikes.
Geologic map unit (-136.051862702096, 59.3196562785067)
Mineral deposit model Polymetallic quartz-sulfide veins (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Age of mineralization The veins must be younger than the Devonian to Mississippian age of the host rocks (Gilbert and others, 1987) and are probably about the same age as the dikes in the area, which are inferred to be 29.3 + 1 to 33.0 + 1 m.y. based on the age of nearby quartz diorite and granodiorite (MacKevett and others, 1974).

Production and reserves

Workings or exploration This occurrence was discovered in 1986 during the Bureau of Mines study reported in Still and others (1991).
Indication of production None

References

MRDS Number 10308246

References

Reporters T.C. Crafford (T. Crafford & Associates, Anchorage)
Last report date 2/4/2001