Prospect, Inactive

Commodities and mineralogy

Main commodities Hg
Other commodities Ag; As; Au
Ore minerals arsenopyrite; cinnabar
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale ID
Quadrangle map, 1:63,360-scale D-1
Latitude 62.85159
Longitude -156.2284
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Joaquin prospect is at an elevation of about 2,200 feet, about 0.7 mile south-southeast of the top of Mount Joaquin. It is about 0.2 mile north-northwest of the center of section 21, T. 32 N., R. 37 W., of the Seward Meridian. The location is accurate. The prospect was approximately located as locality 14 of Cobb (1972 [MF 363]). The published locations of the prospect are ambiguous and it is difficult to locate (T.K. Bundtzen, unpublished field data, 1978).

Geologic setting

Geologic description

The Joaquin prospect consists of thin quartz -sulfide veinlets and stringer zones in a small calcareous sandstone inclusion within the Upper Cretaceous, Mount Joaquin pluton (Malone, 1962; Bundtzen and Laird, 1983). The quartz veinlets contain disseminated grains of cinnabar and arsenopyrite. The prospect is exposed in lichen-covered talus near the toe of a talus fan; the mineralized zone can be traced for about 50 feet along strike and it is about 2 feet thick. The property was staked as a mercury prospect in 1957 but no production has been reported (Malone, 1962). One grab sample from the prospect dump contained 2.00 percent mercury, 240 parts per billion (ppb) gold, 800 ppb silver, and 2.00 percent arsenic (Miller, Bundtzen, and Gray, 2005).
Geologic map unit (-156.230763036161, 62.8509555764234)
Mineral deposit model Polymetallic vein (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Age of mineralization Undated; may be related to emplacement of the Mount Joaquin pluton, which has a 40K/40Ar age of 70.6 Ma (Bundtzen and Laird, 1983).

Production and reserves

Workings or exploration The Mount Joaquin mercury prospect has appeared on many compilations of Alaskan mercury deposits (i.e., Sainsbury and MacKevett, 1965; Malone, 1962). The property was located as a mercury prospect by Knute P. Lind in 1957, but no production has been reported (Malone, 1962). In 1978, a crude pit about 15 feet square that was dug in talus in talus was still visible (T.K. Bundtzen, unpublished field data, 1978).
Indication of production None
Reserve estimates None.
Production notes None recorded, but the site was equipped to be small scale mercury producer in the late 1950s (J. Murphy, oral communication, 1987). A retort was to be assembled on site. A small cabin in a state of disrepair in 1978 was about 1,000 feet from the prospect pit. The cabin contained mallets, sledge hammers, and a small crusher (T.K. Bundtzen, unpublished data, 1978).