West Wing

Prospect, Active

Commodities and mineralogy

Main commodities Au; Cu
Other commodities As; Bi; Fe; Te
Ore minerals arsenopyrite; chalcopyrite; gold; pyrite; pyrrhotite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale TY
Quadrangle map, 1:63,360-scale D-8
Latitude 61.9151
Longitude -152.9557
Nearby scientific data Find additional scientific data near this location
Location and accuracy West Wing is located about 2.7 miles south of Cathedral Mountain; about 0.3 mile north-northeast of the center of section 16, T. 21 N., R. 20 W., of the Seward Meridian. This location is accurate to within 500 feet from the center of the prospect.

Geologic setting

Geologic description

West Wing is a mineralized prospect that is part of the Estelle gold property (TY019). West Wing lies within a plutonic complex intruding a Jurassic to Early Cretaceous flysch sequence (Reed and Nelson, 1980). The intrusive complex consists of ultramafic to felsic plutons of Late Cretaceous/Early Tertiary age (69.7 Ma) and are centrally located in a region of arc-magmatic related gold deposits (Millrock Resources Inc., 2014).
West Wing is characterized by roof pendants of hornfels that are cut by biotite-rich diorite. Hydrothermal breccia, quartz sulfide veins and carbonate veins cut all lithologies. Mineralization occurs as disseminated sulfides and as sulfides associated with veins. The highest sulfide content is associated with a diorite sill containing 1 to 3 percent disseminated arsenopyrite ± pyrite ± chalcopyrite ± pyrrhotite. This unit and the hornfels unit are cut by high density quartz ± pyrite ± chalcopyrite ± arsenopyrite ± pyrrhotite veinlets also containing 1 to 3 percent sulfide, and appears to increase in intensity toward the lower contact of the sill (Millrock Resources Inc., 2014).
Geologic map unit (, )
Mineral deposit model Porphyry Cu-Au or intrusion-related gold? (Cox and Singer, 1986; model 20c)
Mineral deposit model number 20c?
Age of mineralization Late Cretaceous/early Tertiary?; mineralization in the area is thought to be related to the 65 to 66 Ma granodiorite of Mount Estelle (Reed and Lanphere,1972).
Alteration of deposit Hornfelsed sedimentary rocks cut by biotite-rich diorite are cross-cut by hydrothermal breccia, quartz-sulfide veins and carbonate veins (Millrock Resources Inc., 2014).

Production and reserves

Workings or exploration
Geologic mapping in 2012 defined a zone of strong hydrothermal alteration surrounding a diorite sill. At surface, copper, iron and arsenic sulfide mineralization with gold in quartz veins and veinlets appears to increase in intensity toward the lower contact of the sill (Millrock Resources Inc., 2012).
In 2012, soil and rock sampling at West Wing defined multiple surface gold and copper anomalies with individual sample results as high as 18 parts per million (ppm) gold in soil and 108 ppm gold in rock. Composited chip sample results, collected near the site of the 2012 drilling, included 20 meters (66 feet) averaging 0.94 ppm gold and 4050 ppm copper (Millrock Resources Inc., 2014).
Drill results from hole SE12-007 are 0.68 gram of gold per tonne from 50.29 to 61.87 meters, including 1.01 grams of gold per tonne from 50.29 to 57.30 meters. Results from hole SE12-007 are 1.20 grams of gold per tonne from 75.29 to 76.51 meters. Results from SE12-009 are 0.52 gram of gold per tonne from 48.77 to 52.43 meters. Note: Listed composites are those averaging greater than 0.50 gram of gold per tonne calculated using a 0.20 gram of gold per tonne cutoff with a maximum 3 meters internal dilution. Elevated copper values are also present in core from this prospect and range between 1000 and 4580 ppm copper. This newly discovered mineralization appears to be hosted by a shallow dipping diorite dike or sill (Millrock Resources Inc., 2012).
Indication of production None
Reserve estimates None.
Production notes None.

References

References

Millrock Resource, Inc., 2012, Millrock Discovers New Gold Zone at Estelle Project, Alaska: (News release, September 10, 2012) http://www.millrockresources.com/news/millrock-discovers-new-gold-zone-at-estelle-project-alaska (as of December 9, 2014).
Millrock Resource, Inc., 2014, Estelle: http://www.millrockresources.com/projects/estelle/ (as of April 7, 2014).
Reporters V.C. Zinno (Alaska Earth Sciences, Inc.)
Last report date 1/7/2015