|Quadrangle map, 1:250,000-scale||CR|
|Quadrangle map, 1:63,360-scale||D-7|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This prospect is near the shore on the east side of Alikula Bay near its mouth. It is about 1.3 miles east-northeast of Pin Peak and about 0.2 mile northeast of the center of section 1, T. 69 S., R. 72 E. The location is accurate.|
Geologic descriptionThis prospect was briefly noted by Roehm (1942, 1943) but it was largely unrecognized until it was later described and mapped in detail by Still and others (2002). The host rock is Silurian Heceta Limestone that is intruded by an intermediate Cretaceous intrusion a few hundred feet away from the mineralization and mafic dikes up to 50 feet thick. (Eberlein and Churkin, 1983). The mineralization consists of irregular masses of sulfides exposed over a diameter of about 50 feet. The largest surface exposure is about 10 feet by 28 feet in size. The sulfide masses consist of about 80 percent pyrite with pyrrhotite and sphalerite. Still and others (2002) collected 7 samples; the richest taken across 8 feet contained 8,483 parts per billion (ppb) gold, 22.5 parts per million (ppm) silver, 1,173 ppm copper, 7,515 ppm lead, and 4.85 percent zinc. Of the seven samples, six had gold values over 1,200 ppb, all had silver over 10 ppm, lead was over 2,500 ppm in all, and one had more than 1 percent lead. Four of the seven had over 1.4 percent zinc and one had 8.69 percent zinc. All had bismuth over 40 ppm, one had 336 ppm bismuth, and all had high arsenic, antimony and mercury. The sulfides are locally oxidized to gossan but there are no skarn minerals.
|Geologic map unit||(-134.300227519742, 55.9180079827586)|
|Mineral deposit model||Polymetallic replacement deposit in limestone.|
|Age of mineralization||Probably related to a nearby Cretaceous intermediate pluton.|
|Workings or exploration||Known (and staked?) before 1942 but went unrecognized for decades; rediscovered, mapped, and sampled by staff of the U.S. Bureau of Land Management in the late 1990s.|
|Indication of production||None|
Additional commentsThis prospect is now in a Forest Service Wilderness that is closed to mineral exploration and mining.
Eberlein, G. D., Churkin, Michael, Jr., Carter, Claire, Berg, H. C., and Ovenshine, A. T., 1983, Geology of the Craig quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-91, 52 p.
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.
Roehm, J.C., 1943, Strategic and critical mineral occurrences in southeastern Alaska: Alaska Territorial Department of Mines Miscellaneous Report 191-5, 98 p., 11 sheets.
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||D.J. Grybeck (Port Ludlow, WA)|
|Last report date||4/8/2007|