Tolstoi Prospect, Iditarod Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Tolstoi Prospect	Prospect
Iditarod Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: The Tolstoi prospect is at an elevation of about 3,400 feet on a steep saddle at the head one of the headwater tributaries of Tolstoi Creek. It is about 0.5 mile south-southeast of peak 3970 and 0.1 mile northwest of the southeast corner of section 26, T. 33 N., R. 41 W., of the Seward Meridian. The location is accurate.
Geology: The Tolstoi prospect consists of several tabular-to-pipe- shaped, tourmaline-sulfide breccia zones in a cupola of the 70.3 Ma, Beaver Mountains stock (Bundtzen and Laird, 1982; Bundtzen and Miller, 1997). The tourmaline-axinite-quartz breccia bodies are from 6 to 65 feet thick and contain from 1 to 8 percent arsenopyrite, chalcopyrite, and pyrite. Stromeryite and boulangerite, possibly the source of the high silver values in samples, have been identified in polished sections. The Tolstoi prospect is similar to a nearby unnamed prospect (ID006) except that sulfides at the Tolstoi Prospect are more disseminated and the boron metasomatism in the form of tourmaline and axinite is more extensive. Grab samples of the mineralization at the Tolstoi prospect contained up to 10.0 percent copper, 500 parts per million (ppm) silver, 2.0 percent arsenic, more than 2.0 percent lead, 2.0 percent zinc, 1.0 percent antimony, 1,400 parts per billion (ppb) gold, 39 ppm bismuth, 200 ppm cadmium, and 200 ppm tin (McGimsey and others, 1988; Bundtzen and Laird, 1982). Grab samples collected by Battle Mountain Mining Company in 1990 contained up to 1,137 ppb gold, 86.1 ppm silver, 2.03 percent lead, more than 2.00 percent arsenic, and 81 ppm tin (Szumigala, 1993).
Workings: The prospect was mapped and sampled by the Alaska Division of Geological and Geophysical Surveys and the U.S. Geological Survey in from 1979 to 1986. Anaconda Minerals Company sampled and mapped the prospect in 1981 (D. Obolewicz, oral communication, 1981). Noranda Exploration examined the property in 1983 (John Dunbier, oral communication, 1983). The prospect was studied by Battle Mountain Mining Company in 1990 (Szumigala, 1993 and 1996). A geologic description of the Tolstoi prospect is in Bundtzen and Miller (1997).
Age: Undated; may be related to emplacement of the Beaver Mountains stock which has been dated at 70.3 Ma. (Bundtzen and Laird, 1982).
Alteration: Extensive greisen development with tourmaline, quartz, white mica, and fluorite.

Commodities (Major) - Ag, As, Cu; (Minor) - Au, Be, Bi, Cd, Pb, Sb, Sn
Development Status: None
Deposit Model: Sn-polymetallic veins (Cox and Singer, 1986; model 20b).

Other Databases

Link to USGS - Alaska:	ID008

Other Regions, Features and Areas containing this locality

References