Green Wonder

Prospect, Inactive

Commodities and mineralogy

Main commodities Cu; Zn
Other commodities Ag; Cr; Cu; Ni; V
Ore minerals chalcopyrite; pyrite; sphalerite
Gangue minerals diopside; quartz; uvarovite garnet

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-5
Latitude 63.3067
Longitude -146.081
Nearby scientific data Find additional scientific data near this location
Location and accuracy
The Green Wonder prospect is at an elevation of about 4,400 feet about
2.6 miles northeast of the junction of the two forks of Broxson Gulch that diverge just about its mouth. The prospect is about 0.6 mile west-southwest of the center of section 32, T. 18 S., R. 9 E.

Geologic setting

Geologic description

Rose (1965) describes the geology of the area as near the contact of volcanic and sedimentary rocks to the north and Rainy Creek basalt to the south. Nokleberg and others (1992 [MF[; 1992 [Open-File]) assigned the rocks in the area to the Lower Permian to Middle Pennsylvania, Slana Spur Formation. The rocks are intensely faulted and deformed.
As described by Rose (1965) and Bittenbender and others (2007), the occurrence is in an outcrop about 2 feet by 6 feet in size of a bright-green stained, almost white marble with quartz, epidote, uvarovite (green garnet), blebs of epidote, chrome diopside, and traces of sphalerite. The green staining may be garnierite, a secondary nickel mineral. Bittenbender and others (2007) tentatively classify the deposit as a skarn, possibly related to nearby ultramafic rocks based on the presence of nickel and chromium in analyzed samples. Rose's samples contained 10 percent or more zinc, 4 percent chromium, and 2 percent nickel. Samples collected by Bittenbender and his colleagues contained up to 9,980 parts per million (ppm) nickel, 2,190 ppm chromium, and 1,195 ppm zinc.
A 60-foot-wide diabase dike with disseminated chalcopyrite cuts meta-andesite near the prospect (Nokleberg and others, 1991). A sample contained 0.72 percent copper, 0.3 percent vanadium, and 7 ppm silver.
The deposit apparently was found by Moneta-Porcupine prior to 1965. They reportedly did some minor hand trenching but there was little sign of it by the early 2000s. Bittenbender and others (2007) suggest that the prospect may be more of interest to rock collectors for its green marble than as a valuable metal deposit.
Geologic map unit (-146.083262192573, 63.3062796351677)
Mineral deposit model Zinc-nickel-chromium skarn?
Age of mineralization Unclear but younger than the Pennsylvanian or Permian host rocks.
Alteration of deposit Development of quartz-uvarovite-diopside skarn(?) in small marble outcrop.

Production and reserves

Workings or exploration The deposit apparently was found by Moneta-Porcupine prior to 1965. They reportedly did some minor hand trenching but there was little sign of it by the early 2000s. Subsequently examined and sampled by state and federal geologists.
Indication of production None
Reserve estimates None.
Production notes None.

References

MRDS Number A011820

References

Reporters W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS); D.J. Grybeck (Contractor, USGS)
Last report date 5/13/2012