Hanlon

Prospect, Undetermined

Commodities and mineralogy

Main commodities Au
Ore minerals arsenopyrite; gold; pyrite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale SI
Quadrangle map, 1:63,360-scale C-7
Latitude 57.6633
Longitude -136.168
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Hanlon prospect is at sea level on the west shore of Ogden Passage, about 0.6 mile north of Drip Point. The prospect is 0.4 mile west of the center of sec. 34, T. 48 S., R. 57 E. It is location P-65 of Bittenbender and others (1999), location 30 of Cobb (1972, 1978), and MAS no. 0021140044 (U.S. Bureau of Land Management, 2002). The location is accurate within 0.2 mile.

Geologic setting

Geologic description

Johnson and Karl (1985) map the rocks in the area of this prospect as Cretaceous graywacke and argillite interbedded with sparse, lenticular beds of basalt. The rocks are cut by numerous high-angle, mainly northwest-striking faults.
Reed and Coats (1941) report that this prospect, staked in 1933, was explored before WW II by a 25-foot open cut and 50-foot trench. The country rock is graywacke cut by a fault that strikes N40W and dips 80SW. The fault contains up to 5 inches of quartz with pyrite, arsenopyrite, and a little calcite. The arsenopyrite occurs mainly as a replacement in graywacke inclusions in the quartz. Bittenbender and others (1999), citing Still and Weir (1981), report that samples of the mineralization contained up to 0.01 ounce of gold per ton. There is no record of production.
Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler, 1995; Goldfarb, 1997; Goldfarb and others, 1997). ARDF record SI087 provides an overview of the geology of auriferous quartz veins in the Chichagof Mining District.
Geologic map unit (-136.169825728854, 57.6629264452998)
Mineral deposit model Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler and others, 1995; Goldfarb, 1997; Goldfarb and others, 1997).
Alteration of deposit Graywacke inclusions in the quartz are partly replaced by arsenopyrite.

Production and reserves

Workings or exploration The prospect was explored before WW II by a 25-foot open cut and a 50-foot trench.
Indication of production Undetermined
Production notes There is no record of production.

Additional comments

The prospect is in West Chichagof-Yakobi Wilderness.

References

MRDS Number A013269

References

Bittenbender, P., Still, J.C., Maas, K., and McDonald, M., Jr., 1999, Mineral resources of the Chichagof and Baranof Islands area, southeast Alaska: Bureau of Land Management, BLM-Alaska Technical Report 19, 222 p.
Goldfarb, R J., 1997, Metallogenic evolution of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 4-34.
Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Haeussler, P J., Bradley, D., Goldfarb, R., Snee, L., and Taylor, C., 1995, Link between ridge subduction and gold mineralization in southern Alaska: Geology, v. 23, no. 11, p. 995-998.
U.S. Bureau of Land Management, 2002, Alaska mineral locations database report (Sitka quadrangle), July 2, 2002, 205 p. [http://imcg.wr.usgs.gov/dem.html]
Reporters H.C. Berg (U.S. Geological Survey)
Last report date 10/16/2004