Stoney

Prospects, Active

Alternative names

North Stoney
Trundle
Tomahawk
Kid
Stoney Vein

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb
Other commodities As; Sb; Zn
Ore minerals arsenopyrite; chalcocite; chalcopyrite; native copper; galena; gold; pyrite; pyrrhotite; sphalerite; stibnite
Gangue minerals calcite; dolomite; epidote; graphite; quartz; siderite; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale TY
Quadrangle map, 1:63,360-scale D-8
Latitude 61.9115
Longitude -152.9159
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Stoney prospect area is a locally discontinuous 6.8 mile north-northeast trending gold-silver-copper anomaly. The location point is centered on the Stoney Vein about 0.5 mile northwest of Mount Stoney, in the NE1/4 section 15, T. 21 N., R. 20 W., of the Seward Meridian. The location is accurate to within about a half mile.

Geologic setting

Geologic description

The Stoney prospect and others in the vicinity are on the Yentna trend of Late Cretaceous/early Tertiary composite plutons described by Reed and Nelson (1980). The Mount Estelle pluton (Reed and Elliott, 1970) extends from Timber Creek on the south to the Portage Creek area in the north. In the central part of the pluton, a biotite-hornblende-quartz monzonite intrudes Mesozoic marine sedimentary rocks of the Kahiltna terrane.
Two veins follow dilatant zones in the pluton along its west side (Cominco American Incorporated, unpublished reports, 1986-1987). The main Stoney mineralized zone dips steeply and has been traced for more than 3 miles. It is 14 to 60 feet wide and has a vertical relief of at least 1000 feet. The quartz-calcite-dolomite-siderite-tourmaline veins alternate with altered intrusive rocks and the veins contain pyrrhotite, chalcopyrite, arsenopyrite, pyrite, stibnite, and, locally, sphalerite and galena. The North Stoney vein is a sub-parallel feature just west of the northern end of the main Stoney vein. It is up to 35 feet wide and has similar mineralogy to the main Stoney vein. A third vein is one mile to the west.
There was considerable work in the area by government and industry as far back as the 1970's that identified widespread mineralization in the Mount Estelle area (see TY019). From 2005 to 2008, several companies (Hidefield Gold Plc. (2008), International Tower Hill Mines Ltd. (2007) and Millrock Resources Inc. (2008)) have worked in the area and identified several specific prospects. Millrock began exploring the area in 2008 as part of the Estelle project that covers a large block of claims north and south of Mount Estelle. The Stoney vein is within that block and Millrock has sampled it. Hidefield (2008) shows several other veins to the north and south; the Trundle vein and another unnamed vein are about two miles to the north, the Tomahawk vein is about 4 miles to the north, and the Kid vein is about 4 miles the south. All are in the Mount Estelle pluton and are probably similar to the Stoney, Shoeshine (TY032), and Train (TY031) prospects to the south.
Millrock Resources Inc. (2014) reports the Stoney prospect area contains locally discontinuous north-northeast trending gold-silver-copper anomalies defined by both soil and rock samples. The anomalies are all greater than 2.5 kilometers in length with the longest greater than 8 kilometers. The distance from the northernmost to southernmost anomaly is about 11 kilometers. None of the anomalies have been drill tested (Millrock Resources Inc., 2014).
One such anomaly hosts the Stoney vein system, a series of high angle, east-dipping, north-northeast-trending shear-hosted massive sulfide veins. The main Stoney vein varies in width from 1 meter to 3 meters and has a vertical relief greater than 300 meters. The vein follows a greater than 5 kilometer long north-trending dilational shear zone in highly alkaline biotite-hornblende-quartz monzonite. In this location, an intersection of strong northwest-southeast and east-west trending magnetic lineaments coincides with veins of quartz-calcite-dolomite-siderite-tourmaline-pyrrhotite-chalcopyrite-arsenopyrite-pyrite-stibnite ± graphite, chalcocite, native copper, sphalerite and galena. Samples of vein material have returned results up to 11.05 parts per million (ppm) gold. Samples from the nearby T-5 prospect show increased silver and copper values with assays as high as 1,140 ppm silver and 7.43 percent copper (Millrock Resources Inc., 2014).
Geologic map unit (-152.918132678458, 61.9109055484068)
Mineral deposit model Polymetallic vein (Cox and Singer, 1986; model 22c)
Mineral deposit model number 22c
Age of mineralization Late Cretaceous/early Tertiary?; mineralization in the area is thought to be related to the 65-66 Ma, granodiorite of Mount Estelle (Millrock Resources Inc., 2014).
Alteration of deposit Calcite, epidote, sericite, tourmaline, quartz (Millrock Resources Inc., 2014).

Production and reserves

Workings or exploration
There was considerable work in the area by government and industry as far back as the 1970s that identified widespread mineralization in the Mount Estelle area (see TY019). From 2005 to 2008, several companies (Hidefield Gold Plc. (2008), International Tower Hill Mines Ltd. (2007) and Millrock Resources Inc. (2008)) have worked in the area and defined several specific prospects Millrock began exploring the area in 2008 as part of its Estelle project, which covers a large block of claims north and south of Mount Estelle. The Stoney vein is in that block and Millrock has sampled it.
Millrock Resources Inc. (2014) reports the Stoney prospect area contains locally discontinuous north-northeast trending gold-silver-copper defined by both soil and rock samples. The anomalies are all greater than 2.5 kilometers in length with the longest greater than 8 kilometers. The distance from the northernmost to southernmost anomalies is about 11 kilometers. None of the anomalies have been drill tested (Millrock Resources Inc., 2014).
One such anomaly hosts the Stoney vein system, a series of high angle, east-dipping, north-northeast-trending shear-hosted massive sulfide veins. The main Stoney vein varies in width from 1 meter to 3 meters and has a vertical relief greater than 300 meters. The vein follows a greater than 5 kilometers long north-trending dilational shear zone in highly alkaline biotite-hornblende-quartz monzonite. In this location, an intersection of strong northwest-southeast and east-west trending magnetic lineaments coincides with veins of quartz-calcite-dolomite-siderite-tourmaline-pyrrhotite-chalcopyrite-arsenopyrite-pyrite-stibnite ± graphite, chalcocite, native copper, sphalerite and galena. Samples of vein material have returned results up to 11.05 parts per million (ppm) gold. Samples from the nearby T-5 prospect show increased silver and copper values with assays as high as 1,140 ppm silver and 7.43 percent copper (Millrock Resources Inc., 2014).
Indication of production None
Reserve estimates None.
Production notes None.

References

MRDS Number A106256

References

Hidefield Gold Plc., 2008, South Estelle: http://www.hidefieldgold.com/s/SouthEstelle.asp (as of May 25, 2008).
International Tower Hill Mines Ltd., 2007, ITH further defines mineralization at South Estelle: (News release, October 18, 2007) http://www.ithmines.com/archives/past_news_releases/index.php?&content_id=165 (as of January 7, 2015).
Millrock Resources Inc., 2008, Estelle: http://www.millrockresources.com/index.php/projects/estelle/ (as of May 25, 2008).
Millrock Resources Inc., 2014, Estelle: http://www.millrockresources.com/projects/estelle/ (as of April 9, 2014).
Reporters Madelyn A. Millholland (Anchorage); D.J. Grybeck (Port Ludlow, WA); V.C. Zinno (Alaska Earth Sciences, Inc.)
Last report date 1/8/2015