DZ

Prospect, Active

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Cu; Pb; Zn
Ore minerals pyrite
Gangue minerals calcite; chlorite; ferroan dolomite; quartz

Geographic location

Quadrangle map, 1:250,000-scale JU
Quadrangle map, 1:63,360-scale D-4
Latitude 58.8491
Longitude -135.0291
Nearby scientific data Find additional scientific data near this location
Location and accuracy The DZ prospect is at an elevation of about 2,350 feet, on the ridge northeast of upper Johnson Creek. It is about 2 miles south-southeast of Lions Head Mountain near the center of section 11, T. 35 S., R. 62 E. of the Copper River Meridian. The location is accurate.

Geologic setting

Geologic description

Note: Beginning in the 1990s, this and other old mines and prospects in the vicinity were consolidated by Coeur-Alaska into a single property (Birak, 2006). They have carried out major new drilling and underground exploration that better defines the mineralization, largely blurs the geologic distinction among the old deposits, and extends the ore bodies greatly. They have developed a coherent modern interpretation of the mineralization as a single deposit which Coeur-Alaska intends to mine as a unit. This deposit is described separately in ARDF as the Jualin (Coeur-Alaska) deposit (JU262). For geologic reference purposes and for their historic value, the pre-Coeur-Alaska data for this and the other old mines and prospects that Coeur-Alaska consolidated are retained in ARDF.
In 1984, Bear Creek Mining Company identified a N40W-trending, 300- to 800-foot-wide band of quartz veins with disseminated pyrite, that is now called the DZ prospect. The veins carry elevated gold values, accompanied by wallrock alteration similar in style to that at the Jualin Mine (JU044) and Kensington Mine (JU029) (Barnett, 1989). The veins at the DZ prospect are traceable for over 7,000 feet. Bear Creek collected 140 vein samples of which nearly 20 percent assayed 0.05 ounce or more gold per ton; the highest was 1.205 ounces of gold per ton. In 1987 and 1988 additional mapping and sampling was conducted by International Curator Resources, Ltd. (Barnett, 1989).
Geologic map unit (-135.030911075997, 58.8487730084439)
Mineral deposit model Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization The age of mineralization in the Berners Bay district is about 55 Ma, the same as the other mesothermal gold-quartz-vein deposits in the Juneau Gold Belt (Goldfarb and others, 1997).
Alteration of deposit The alteration adjacent to the veins is characterized by reddish-brown ferroan dolomite alteration, sericitization of plagioclase, chloritization and sulfidization of mafic minerals, and albitization of feldspars (Leveille, 1991).

Production and reserves

Workings or exploration The DZ deposit was discovered and sampled by Bear Creek Mining Company in 1984. International Curator Resources and Placer Dome U.S. conducted additional mapping and sampling in 1987 and 1988.
Indication of production None

References

References

Barnett, J.C., 1989, Jualin gold project, 1988 progress report, Berners Bay District: Unpublished report for International Curator Resources, Ltd., 75 p.
Birak, D.J., 2006, Kensington gold project: Unpublished Technical Report for Cour d'Alene Mines, 116 p. (posted on www/.sedar.com, April 20, 2006).
Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Leveille, R.A., 1991, Geology and gold deposits of the Jualin mine area, Berners Bay district, southeastern Alaska: Fairbanks, University of Alaska, M.S. thesis, 200 p.
Miller, L.D., Goldfarb, R.J., Snee, L.W., Gent, C.A., and Kirkham, R.A., 1995, Structural geology, age, and mechanisms of gold vein formation at the Kensington and Jualin deposits, Berners Bay district, southeast Alaska: Economic Geology, v. 90, p. 343-368.
Reporters J.C. Barnett and L.D. Miller (Juneau, Alaska ); D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008