Unnamed (North Marble Island)

Prospect, Inactive

Commodities and mineralogy

Main commodities Fe; Ni; Zn
Other commodities Cu
Ore minerals chalcopyrite; covellite; magnetite; pyrite; pyrrhotite; sphalerite

Geographic location

Quadrangle map, 1:250,000-scale MF
Quadrangle map, 1:63,360-scale C-1
Latitude 58.672
Longitude -136.061
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect site is on North Marble Island in Glacier Bay about 3.5 miles southwest of Sandy Cove. The location is uncertain; MacKevett and others (1971) did not find Reed's (1938) or Rossman's (1963) locations. The island is only about 0.4 mile long and 0.2 mile wide, and the location is probably correct to about 0.10 mile. The occurrence is location number 50 of Cobb (1972).

Geologic setting

Geologic description

North Marble Island is underlain mainly by crystalline marble that is part of a major marble unit exposed on several islands in Glacier Bay. They include Willoughby, Francis, and Drake Islands as well as North and South Marble Islands. The carbonate-rich section is primarily Devonian in age (MacKevett and others, 1971; Brew and others, 1978). The age of metamorphism and mineralization is probably Cretaceous. Assuming that the area is underlain by the granitic batholith of Cretaceous age that characterizes this province.
Small sulfide (chalcopyrite, covellite, magnetite, pyrite, pyrrhotite?, and/or sphalerite) pods, commonly associated with mafic dikes, are widely distributed throughout the province. On North Marble Island, sulfide pods as much as 1.5 ft wide and 15 feet long occur in marble near mafic dikes. The sulfides also occur on joint faces within the dikes (Reed, 1938, p. 69). A mass of sphalerite and magnetite at an unspecified contact (?) was reported by Rossman (1963, p. K51).
Geologic map unit (-136.062856000346, 58.6716310897836)
Mineral deposit model Distal hydrothermal replacement possibly related to subjacent granitic intrusions of Cretaceous age.
Age of mineralization Cretaceous?

Production and reserves

Workings or exploration No workings. One claim reportedly located for nickel by S. H. Vevelstad before 1930. Burchard (1914, 1920), who investigated the area for the marble resource, reported mafic or lamprophyric dike rocks cutting marble.
Indication of production None

Additional comments

The site is in Glacier Bay National Park and Preserve.
The first known metallic prospect staked on the island was by S. H. Vevelstad before 1930, who reportedly staked it for nickel. Mr. Vevelstad was an experienced prospector, better known for his discoveries of nickel-copper deposits in the Bohemia Basin area in the Sitka quadrangle.

References

MRDS Number 10307815

References

Reporters C.C. Hawley (Hawley Resource Group)
Last report date 1/3/1999