Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Au
Other commodities As; Cu; Pb; Zn
Ore minerals arsenopyrite; galena; jamesonite; limonite; pyrite; scorodite; sphalerite; stibiconite
Gangue minerals calcite; clay; quartz

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-2
Latitude 63.552
Longitude -150.8838
Nearby scientific data Find additional scientific data near this location
Location and accuracy
The Chloride prospect is at an elevation of about 3200 to 3500 feet, on the south flank of the ridge east of the head of Lucky Gulch. The Chloride claim abuts the Jupiter-Mars claim (MM102), and is in the center of the SW1/4 SE1/4, section 5, T. 16 S., R. 17 W., Fairbanks Meridian. The site is at the approximate discovery cut and is accurate within about 300 feet.
The Chloride (called the Chlorine) prospect corresponds to location 37 of Bundtzen (1981), and occurrence 55 of Thornsberry, McKee, and Salisbury (1984). Thornsberry, McKee, and Salisbury (1984, loc. 51) show the Chloride prospect on their map of the Jupiter-Mars prospect.

Geologic setting

Geologic description

The country rock at the Chloride prospect is mainly metafelsite of the lower Paleozoic Spruce Creek sequence (Bundtzen, 1981). Chloritic phyllite crops out at the eastern end of the Chloride claim, and a Tertiary diabase dike crops out north of its eastern end (Thornsberry, McKee, and Salisbury, 1984, v. 2, map of occurrence 51).
The Chloride deposit is a mineralized shear zone containing sulfide-bearing, quartz-calcite-clay veins and stringers. Float, rubble crop, and soil analyses indicate that the zone is as much as 800 feet wide and generally is at least 100 feet wide. The zone strikes N70-75E on the western part of the Chloride claim, and about N80-85E near its east end. The zone, as confirmed in drill holes, is nearly vertical. The ore minerals are mainly arsenopyrite and pyrite. Galena is locally abundant, and sphalerite, apparently dissolved from most of the surface ore, occurs in drill core. Assays show 1 to 5 percent arsenic, up to 20 percent lead, and 3.55 percent zinc. Limonite and scorodite(?) are locally abundant near-surface oxidation products. A zinc halo, marked by zinc assays greater than 0.1 percent, surrounds the deposit. Quartz at the surface commonly is limonite stained, vuggy, and brecciated. Including mineralization on the Jupiter-Mars claim, Thornsberry, McKee, and Salisbury (1984, v. 2, occurrence 55) estimated a resource of 103,760 tons or ore grading 0.062 ounce of gold per ton and 5.97 ounces of silver per ton.
In 1983, the U.S. Bureau of Mines drilled two core holes (K-12 and K-14) on the Chloride claim (Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrences 51 and 55, and drill logs). Hole K-12 was drilled northerly across the lode from near the midpoint of the south claim sideline. Between 215 feet and 268 feet, the hole intersected mineralized quartz breccia and sheared, silicified metafelsite. The richest part of this intercept is between 224.7 and 226.5 feet, which assayed 0.063 ounce of gold per ton, 7.31 ounces of silver per ton, and 4.15 percent lead. The average assay of about 52 feet of core commencing at 215 feet was 0.017 ounce of gold per ton, 0.656 ounce of silver per ton, 0.11 percent copper, 0.86 percent lead, 0.76 percent zinc, and 1.2 percent arsenic. Core recovery was relatively poor, and the values are probably minimal. Drill hole K-14, collared about 300 feet east-northeast of hole K-12, encountered a similar section. An intercept of 54 feet commencing at 309.2 feet averaged 0.014 ounce of gold per ton, 2.15 percent zinc, and 1.2 percent arsenic (Thornsberry, McKee, and Salisbury, 1984, v. 2). Silver either was not determined or not reported in hole K-14.
Zinc is nearly ubiquitous. Most check assays of core in hole K-14 from 75 feet to 309.2 feet exceed 0.1 percent zinc, as do check assays of core in hole K-12 from 110 feet to 215 feet. In these intervals, the metafelsite hostrock is argillized and cut by thin veinlets of quartz, calcite, and clay.
Geologic map unit (-150.886085983901, 63.5514952352624)
Mineral deposit model Low-sulfide Au-quartz vein, possibly grading into a polymetallic vein (Cox and Singer, 1986; models 39a and 22c?).
Mineral deposit model number 39a, 22c?
Age of mineralization The deposit is assumed to be Eocene (see record MM091).
Alteration of deposit Extensive silicification and argillization of the metafelsite hostrock. Oxidation of iron and arsenic minerals.

Production and reserves

Workings or exploration William Taylor probably prospected the Chloride deposit in the 1920s, at the same time that he explored the Jupiter-Mars (then the Damon and Pythias) deposit (Wells, 1933). In 1976, Hawley and Associates (1978, fig. 4.1-A(1)-4) conducted a soil survey on the Chloride and Jupiter-Mars claims. In 1983, the U.S. Bureau of Mines drilled two holes on the Chloride claim (Thornsberry, McKee, and Salisbury, 1984, v. 2).
Indication of production None
Reserve estimates
Thornsberry, McKee, and Salisbury (1984, v. 2) computed a partly drill- based resource of 103,760 tons of ore grading 0.062 ounce of gold per ton, 5.97 ounces of silver per ton, and significant lead and zinc. A larger resource can be inferred from the extent of mineralization on the claim. Based on a width of 50 feet, strike length of 1000 feet, depth of 500 feet, and estimated average of surface and subsurface sample assays, there is a resource of about 2,000,000 tons of rock grading about 0.025 ounce of gold per ton and 1 ounce of silver per ton.
The low-grade, gold-silver deposit at the Chloride prospect probably is the best-defined bulk-mineable target in the Kantishna Hills lode area (MM091). The deposit would have been too low-grade and remote to mine when the nearby Banjo deposit was being mined in 1939-41, but it is within the grade and tonnage range of a modern, small, open-pit mine. Drilling, metallurgical study, and other research would be required to define an economic deposit.

Additional comments

The Chloride prospect is in Denali National Park and Preserve.