Prospect, Probably inactive

Commodities and mineralogy

Main commodities As; Ba; Pb; Zn
Ore minerals barite; galena; pyrite; witherite
Gangue minerals limestone

Geographic location

Quadrangle map, 1:250,000-scale PA
Quadrangle map, 1:63,360-scale D-1
Latitude 56.90148
Longitude -134.08026
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect includes several claims and a test pit on mineralization at the east end of a small island south of the Keku Islands and just north of the peninsula north of Saginaw Bay. The prospect is about 6.8 miles east-southeast of Cornwallis Point; it is in the north half of section 28, T. 57 S., R. 72 E.

Geologic setting

Geologic description

This prospect is one of a group of similar deposits (PA021 to PA031) that are scattered along the south shore of Saginaw Bay, on the peninsula north of Saginaw Bay, and on the Keku Islands. They occur in a heterogeneous section of unmetamorphosed volcanic, carbonate, and clastic rocks that vary in age from Silurian to Triassic (Muffler, 1967). The mineralization generally consists of veins, veinlets, and irregular pods that contain base metals and barite (Still and others, 2002). There are no plutonic rocks in the immediate vicinity; however, the sedimentary rocks are cut by scattered gabbro dikes. The origin of the deposits is uncertain although most appear to be epigenetic. Various origins have been proposed including that they are remobilized massive-sulfide deposits, that they are related to a buried intrusive, or that they are Mississippi-Valley-type deposits.
This prospect was known before 1925 and was staked intermittently until at least 1953. The only working is a small test pit. The rocks in the area consist of limestone, part of the the Kuiu Limestone of Silurian age, that is cut by gabbro dikes (Muffler, 1967). The limestone is cut by short veins, stringers, and pods of barite, witherite, and pyrite. Still and others (2002) sampled several occurrences on the small island on which the deposits occur. At the northwest end of the island, a barite stringer about 1.5 feet wide contained 3.2 percent zinc, 2,355 parts per million (ppm) lead and 24.22 percent barite. At the northeast end of the island, a mineralized zone 50 feet wide extends for about 50 feet before it disappears under the water. The zone contains stringers of barite and pyrite with rare galena, and pods of pyrite up to 0.6 feet wide and 1.0 feet long. A pod of barite with pyrite contained 1,602 ppm arsenic, and 7,107 ppm barium. A pyrite lens contained 1,725 ppm arsenic and 8,498 ppm barium.
Geologic map unit (-134.081982254643, 56.9011446021432)
Mineral deposit model Stringers and pods of barite, witherite, and pyrite in limestone.
Age of mineralization Younger than the Silurian to Triassic host rocks.

Production and reserves

Workings or exploration This prospect was known before 1925 and was staked intermittently until at least 1953. The only working is a small test pit.
Indication of production None
Reserve estimates None.

Additional comments

MAS number: 0021160013.


MRDS Number A013382


Reporters Donald J. Grybeck (U.S. Geological Survey)
Last report date 2-Jan-05