|Quadrangle map, 1:250,000-scale||DN|
|Quadrangle map, 1:63,360-scale||C-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||
The Florence prospect (Cobb, 1980 [OFR 80-363]) is on the north spur of Wickersham Dome at an elevation of about 3550 feet. It is in the SW1/4 NE1/4 section 6, T. 15 S., R. 17 W., Fairbanks Meridian. The location is accurate within 300 feet.The prospect corresponds to number 12 of Cobb (1972 [MF 366]), 39 of Bundtzen (1981), 44 of Thornsberry, McKee, and Salisbury (1984), and 110 of Hawley and Associates (1978). This site also includes a possibly related prospect a few hundred feet north of the Florence prospect. It is number 45 of Thornsberry, McKee, and Salisbury (1981), possibly number 40 of Bundtzen (1981), and general location 12 of Cobb (1972 [MF 366]), and may be the Caribou Horn claim of Carl Wikstrom (Heiner and Porter, 1972: KX 66-46).
The country rock at the Florence prospect is quartz mica schist of the Precambrian Birch Creek Schist (Bundtzen, 1981; Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 44). Exposures are poor, but the trace of float across the area suggests that the deposit is a sulfide-bearing quartz-siderite vein that strikes about N 40 E. A shaft and trench were caved by 1931, when Wells (1933, p. 370) visited the Florence property. He reported fine-grained galena and tetrahedrite, and that the rocks were stained with malachite. The prospect subsequently was explored by bulldozer trenches, which exposed oxidized ore that contained abundant anglesite, azurite, cerussite, goethite, and malachite. Bundtzen (1981) reported sphalerite, stibnite, and polybasite in remnant fragments of fresh ore.
Some of the ore is moderately rich in silver that seems to be associated with galena, but there is essentially no gold. The richest sample assayed 70 ounces of silver per ton and 70 percent lead. Another sample containing only 4.55 percent lead assayed almost 40 ounces of silver per ton. Both samples contained about 1.5 percent copper, suggesting that tetrahedrite or another copper-bearing mineral is present (Bundtzen, 1981; Thornsberry, McKee, and Salisbury, 1984, v. 2). Samples collected by Hawley and Associates (1978) contained up to 50 percent lead, 1.35 percent copper, 5.2 percent zinc, and 3.1 percent antimony.A vein possibly related to the Florence vein is exposed several hundred feet north of the Florence prospect (Thornsberry, McKee, and Salisbury, 1984, v. 2, no. 45). It contains pyrite, galena, stibnite, and stibiconite. Maximum assay values for base metals were in the 0.X range.
|Geologic map unit||(, )|
|Mineral deposit model||Polymetallic vein (Cox and Singer, 1986; model 22c).|
|Mineral deposit model number||22c|
|Age of mineralization||The deposit is assumed to be Eocene (see record DN091).|
|Alteration of deposit||Oxidation of iron, copper, lead, and antimony minerals.|
|Workings or exploration||The prospect was explored by a shallow shaft and trenches, which were caved and sloughed by 1931 (Wells, 1933). More recently, possibly in the 1970s, it was explored by shallow bulldozer trenches and a stripped circular area about 150 feet in diameter.|
|Indication of production||None|
Additional commentsThe prospect is in Denali National Park and Preserve.
Bundtzen, T.K., 1981, Geology and mineral deposits of the Kantishna Hills, Mt. McKinley quadrangle, Alaska: M. S. Thesis, University of Alaska, College, Alaska, 238 p.
Cobb, E. H., 1972, Metallic mineral resources map of the Mount McKinley quadrangle, Alaska: U. S. Geological Survey Miscellaneous Field Studies Map MF-366, 1 sheet, scale 1:250,000.
Cobb, E.H., 1980, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mount McKinley quadrangle, Alaska: U. S. Geological Survey Open-File Report 80-363, 150 p.
Cox, D.P., and Singer, D.A., eds., 1986, Mineral deposit models: U.S. Geological Survey Bulletin 1693, 379 p.
Hawley, C. C. and Associates, Inc, 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska: U. S. Bureau of Mines Open-File Report 24-78, 275 p. (paged by sections).
Heiner, L.E., and Porter, Eve, 1972, Alaska Mineral Properties, volume 2: University of Alaska, Mineral Industry Research Laboratory Report 24, 669 p.
Thornsberry, V. V., McKee, C. J., and Salisbury, W. G., eds, 1984, 1983 Mineral Resource Studies: Kantishna Hills and Dunkle Mine Areas, Denali National Park and Preserve, Alaska: U. S. Bureau of Mines Open-File Report 129-84. 3 Volumes: v. 1, Text; v. 2, Appendices; v. 3, Maps. Prepared by Salisbury & Dietz, Inc., Spokane, WA.
|Last report date||4/29/2001|