Unnamed (on Saginaw Bay)

Occurrence, Probably inactive

Commodities and mineralogy

Main commodities Ba
Ore minerals barite; witherite
Gangue minerals calcite

Geographic location

Quadrangle map, 1:250,000-scale PA
Quadrangle map, 1:63,360-scale D-1
Latitude 56.87062
Longitude -134.21784
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is near the middle of the southwest shoreline of Saginaw Bay. It is about 1.8 miles southeast of Sachem Island and about 0.3 mile north-northwest of the center of section 3, T. 58 S., R. 71 E. The location is accurate.

Geologic setting

Geologic description

This occurrence 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 occurrence was first mentioned by Buddington (1925) but there is no indication that claims have ever been staked on it or that it has been explored. The occurrence is in thin-bedded limestone of the Silurian Kuiu Limestone (Muffler, 1967). Barite occurs in widely spaced, subparallel veins that pinch and swell and vary from stringers to 2.5 feet wide (Still and others, 2002). The longest can be traced for 20 feet. The veins are composed of pinkish-white blades of barite with calcite and probably witherite. There are no reports of significant base metals.
Geologic map unit (-134.219562394256, 56.8702840615675)
Mineral deposit model Barite veins.
Age of mineralization Younger than the Silurian host rock.

Production and reserves

Workings or exploration This occurrence was first mentioned by Buddington (1925) but there is no indication that claims have ever been staked on it or that it has been explored.
Indication of production None
Reserve estimates None.

Additional comments

MAS number: 0021160015.

References

MRDS Number A013375

References

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