Florence

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Pb
Other commodities Au; Cu; Sb; Zn
Ore minerals anglesite; azurite; cerussite; galena; goethite; malachite; polybasite; pyrite; sphalerite; stibiconite; stibnite; tetrahedrite
Gangue minerals quartz; siderite

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-2
Latitude 63.5591
Longitude -150.9127
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).

Geologic setting

Geologic description

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 (-150.914987624625, 63.5585945649258)
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 MM091).
Alteration of deposit Oxidation of iron, copper, lead, and antimony minerals.

Production and reserves

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 comments

The prospect is in Denali National Park and Preserve.

References

MRDS Number A011212

References

Reporters C.C. Hawley
Last report date 4/29/2001