Prospect, Active

Commodities and mineralogy

Main commodities Ag; Au
Other commodities Cu; Pb; Zn
Ore minerals arsenopyrite; pyrite (and probably others)
Gangue minerals quartz; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale TY
Quadrangle map, 1:63,360-scale D-8
Latitude 61.8314
Longitude -152.9157
Nearby scientific data Find additional scientific data near this location
Location and accuracy The center of the Train prospect is about 1.5 miles south of Mount Estelle; it is about 0.5 mile south of the center of section 9, T 20 N., R. 20 W. The location is accurate.

Geologic setting

Geologic description

The Train prospect is near the periphery of the Cretaceous (65-66 Ma) Mount Estelle pluton, which is zoned from a granite core to marginal phases of quartz monzonite, quartz monzodiorite, augite monzodiorite, diorite and lamprophyric mafic and ultramafic rocks (Reed and Elliott, 1970; Millholland, 1995; Crowe and others, 1991; Crowe and Millholland, 1990). The pluton intrudes Jurassic and Cretaceous sedimentary rocks that are hornfelsed adjacent to the pluton, are locally stained red, and have been altered to sericite and clay. Pyrite occurs as disseminations and along fractures.
There was considerable work in the area by government and industry as far back as the 1970s that identified mineralization, but the work was more general than prospect specific (see TY019). From 2005 to 2008, several companies, Hidefield Gold Plc. (2008), International Tower Hill Mines Ltd. (2007) and Millrock Resources Inc. (2008), have defined several specific prospects in the area, including the Train prospect and the nearby Shoeshine prospect (TY032). Millrock is currently (2008) exploring the deposit as part of its Estelle project that covers a large block of claims north and south of Mount Estelle.
International Tower Hills collected a sample of a quartz-sulfide vein at the Train prospect that contained 57 parts per million (ppm) gold, 212 ppm silver, 3.6 ppm copper, and 0.3 ppm lead. The vein trends north and dips steeply. Millrock collected numerous samples along a north- to north-northeast trending zone about 1.5 miles long; many of the samples contained more than 2 grams of gold per ton. Of the 83 samples they collected, the average gold content was 7.61 grams per tonne; the minimum was 0.01 gram per ton, and the highest was 56.9 grams per tonne. The possible porphyry-style mineralization consists mainly of quartz-arsenopyrite veins; auriferous quartz stockworks; and breccia zones cemented by quartz, oxidized sulfides, and tourmaline.
Geologic map unit (-152.9179216041, 61.8308023370758)
Mineral deposit model Gold-arsenopyrite-quartz veins, stockworks, and breccias.
Age of mineralization Later than the 65-66 Ma Mount Estelle pluton that hosts the mineralization; may be genetically related to the pluton.
Alteration of deposit The alteration associated with the quartz veins, stockworks, and breccia is not specifically noted.

Production and reserves

Workings or exploration Limited sampling by a succession of companies since the 1970s.
Indication of production None



Crowe, D.E., and Millholland, M.A., 1990, High-grade gold mineralization associated with high salinity hydrothermal fluids, Mt. Estelle pluton, central Alaska Range [abs.]: Geological Society of America, Abstracts with Programs, v. 22, p. A41.
Hidefield Gold Plc., 2008, South Estelle: (as of May 25, 2008)
International Tower Hill Mines Ltd., 2007, ITH further defines mineralization at South Estelle: (News release, October 18, 2007)
Millholland, M.A., 1995, Geology and discovery at Mount Estelle: Newsletter of the Alaska Geological Society, v. 24, no. 8, p. 1.
Millrock Resources Inc., 2008, Estelle: (as of May 25, 2008).
Reporters D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008