|Quadrangle map, 1:250,000-scale||PA|
|Quadrangle map, 1:63,360-scale||A-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This occurrence is about 0.8 mile west-northwest of Mount Howard and about 0.3 mile east of the northwest corner of section 31, T. 66 S. R. 73 E. Figure 6 of Still and others (2002) is a map of the deposit; the location is accurate.|
Geologic descriptionThis occurrence was first described by Roehm (1942) and was recently mapped and sampled by Still and others (2002). The deposit consists of several quartz veins with an aggregate thickness of about 6 feet. The veins are associated with a fault zone and are generally parallel to the bedding of the folded host rocks, which are limestone, silty limestone, and chert. The rocks are part of the Bay of Pillars Formation of Silurian age (Brew and others, 1984). A large Cretaceous hornblende quartz monzonite crops out about a mile to the east. The veins, fault zone, and strata generally strike N60W and dip 75 SW to vertical. The veins contain irregular masses, bands, and disseminations of pyrite with minor sphalerite and galena. The highest grade sample collected by Still and others (2002) across 1.3 feet of a quartz vein contained 134 parts per billion gold, 2,959 parts per million (ppm) zinc, and 1,264 ppm arsenic. Another sample contained 15 ppm silver and 353 ppm lead across 0.7 feet and a sulfide-rich sample collected in the quartz vein contained 25.2 ppm silver, 1,153 ppm copper, 8,692 ppm lead and 14,558 ppm zinc.
|Geologic map unit||(-134.18221840668, 56.1098134619463)|
|Mineral deposit model||Polymetallic quartz vein (Cox and Singer, 1986; model 22c).|
|Mineral deposit model number||22c|
|Age of mineralization||The veins cut Silurian strata and may be related to a nearby Cretaceous quartz monzonite stock.|
|Workings or exploration||Only surface sampling.|
|Indication of production||None|
Brew, D.A., Ovenshine, A.T., Karl, S.M., and Hunt, S.J., 1984, Preliminary reconnaissance geologic map of the Petersburg and parts of the Port Alexander and Sumdum 1:250,000 quadrangles, southeastern Alaska: U.S. Geological Survey Open-File Report 84-405, 43 p., 2 sheets, scale 1:250,000.
Roehm, J.C., 1942, Summary report of mining investigations and itinerary of J. C. Roehm in the Ketchikan, Wrangell, Petersburg and Juneau mining precincts: Alaska Territorial Department of Mines Itinerary Report 195-33, 23 p.
Still, J.C., Bittenbender, P.E., Bean, K.W., and Gensler, E.G., 2002 Mineral assessment of the Stikine area, central Southeast Alaska: U.S. Bureau of Land Management Technical Report 51, 560 p.
|Reporters||Donald J. Grybeck (U.S. Geological Survey)|
|Last report date||2-Jan-05|