Glenn Gulch; Mohawk Prospect, Iditarod District, Yukon-Koyukuk Borough, Alaska, USA
This page is currently not sponsored. Click here to sponsor this page.
Geology: The Glen Gulch prospect is a steeply-inclined quartz-sulfide vein that is exposed in the Otter Creek placer mine (ID111). The lode consists of sulfide-quartz mineralization in a N5-8E steeply dipping shear zone that cuts monzonite of the 68.7 Ma, Black Creek stock (Bundtzen and others, 1992; Miller and Bundtzen, 1994). The zone can be traced along strike for about 180 feet where it is buried under placer tailings on one end and under vegetation on the other. Major stibnite and arsenopyrite are readily identified in the field. Microprobe studies by Bundtzen and others (1992) also indicates the presence of the silver-antimony-lead sulfosalt, diaphorite, as well as kermesite, and two other unidentifiable silver sulfosalt minerals (Bart Cannon, oral communication, 1991). The mineralization formed during multiple hydrothermal events. Early arsenopyrite is brecciated and cut by stibnite and diaphorite. Brooks (1916) also identified minor cinnabar. Chip and channel samples from the vein contain up to 8.6 parts per million (ppm) gold, 1,019 ppm silver, 36.7 percent antimony, 2,101 ppm copper, 999 ppm lead, more than 2,000 ppm arsenic, 15 ppm bismuth, 135 ppm tungsten, more than 5.0 ppm mercury, and 516 ppm zinc (Bundtzen and others, 1992).
Workings: The Glenn Gulch prospect was first described by Brooks (1916), and later by Mertie and Harrington (1924), who referred to the prospect as the Mohawk Lode. The U.S. Geological Survey and Alaska Division of Geological and Geophysical Surveys mapped and sampled the site in 1988 (Bundtzen and others, 1992).
Age: Unknown; the Black Creek stock that hosts the vein is 68.9 Ma (Bundtzen and others, 1992).
Production: No lode production; the gold mined from placers above the lode is included with Otter Creek placer mine (ID111).
Commodities (Major) - Ag, Au, Sb; (Minor) - Bi, Cu, Hg, Pb, W, Zn
Development Status: None
Deposit Model: Polymetallic vein (Cox and Singer, 1986; model 22c).
5 entries listed. 5 valid minerals.
The above list contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.
Brooks, A.H., 1916, Antimony deposits of Alaska: U.S. Geological Survey Bulletin 649, 67 p. Bundtzen, T.K., Miller, M.L., Laird, G.M., and Bull, K.F., 1992, Geology and mineral resources of Iditarod mining district, Iditarod B-4 and eastern B-5 quadrangles, southwestern Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 97, 46 p., 2 sheets, scale 1:63,360. Mertie, J.B., Jr., and Harrington, G.L., 1924, The Ruby-Kuskokwim Region, Alaska: U.S. Geological Survey Bulletin 754, 129 p. Miller, M.L., and Bundtzen, T.K., 1994, Generalized geologic map of the Iditarod quadrangle, Alaska showing potassium-argon, major oxide, trace element, fossil, paleocurrent, and archeological sample localities: U.S. Geological Survey Miscellaneous Field Studies Map MF-2219-A, 48 pages; 1 sheet, scale 1:250,000.