Prospect, Active

Alternative names


Commodities and mineralogy

Main commodities Ag; Au
Other commodities As; Cu; Hg; Pb; Sb; Zn
Ore minerals chalcopyrite; galena; gold; galena; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale PM
Quadrangle map, 1:63,360-scale A-2
Latitude 55.19
Longitude -160.654
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Aquila prospect is located on southeastern Unga Island one mile east of Acheredin Bay (Nokleberg and others, 1987, locality AP3; Wilson and others, 1988, locality 37). The map site is at an elevation just over 700 feet, 0.25 mile north of the center of sec. 3, T. 58 S., R. 75 W. of the Seward Meridian. The location is accurate.

Geologic setting

Geologic description

The Aquila prospect is one of several northeast-striking epithermal vein systems in an area approximately 1,000 by 2,000 feet. The systems include veins on the Origin (PM087), Freds (PM088), Surprise (PM089), Ankle Creek (PM090), Altair (PM091), and Amethyst (PM092) prospects.
The Aquila vein system cuts andesite flows and tuffs of the late Eocene to early Oligocene Popof volcanic rocks (Wilson and others, 1995). It is as much as 100 feet in width and can be traced along strike for as much as 2,000 feet. It exhibits evidence of open-space filling and repeated phases of fracturing and deposition, resulting in vein breccias and quartz stockworks (Peterson and others, 1982). The veins contain pyrite, and, locally free gold, along with trace amounts of chalcopyrite, galena, and sphalerite.
Many sets of lineaments characterize the prospect area. The widest and richest zones of veins seem to occur at the intersection of these lineaments with northwest-striking faults. Higher gold values are also associated with zones of multiple brecciation. The gold is free-milling and ranges in size from 20 to 40 microns (Peterson and others, 1982).
Geologic map unit (-160.656067080617, 55.189163762451)
Mineral deposit model Sado-type epithermal gold vein (Cox and Singer, 1986; model 25d).
Mineral deposit model number 25d
Age of mineralization Eocene or younger, based on the age of the host rock (Wilson and others, 1995).
Alteration of deposit The alteration is zoned outward from the veins from silicification to argillization to propylitization (source unknown, from previous reporting).

Production and reserves

Workings or exploration
This prospect was explored by Resource Associates of Alaska and UNC Teton Exploration Drilling Company during the period 1979 to 1982. During that time they mapped the area; conducted magnetometer, Very Low Frequency Electromagnetic (VLF-EM) and Induced Polarization (IP) surveys; drilled 12 core holes for a total of 4,446 feet; collected 675 rock samples; cut 17 trenches for a total of 3,310 feet; and took 472 trench samples. Precious metal values in trench samples include 0.335 ounce per ton (oz/t) gold and 1.56 oz/t silver over 12 feet, 0.242 oz/t gold and 0.68 oz/t silver over 12 feet, 0.105 oz/t gold and 0.17 oz/t silver 12 feet, and 0.165 oz/t gold and 0.18 oz/t silver 10 feet. Selected drill core assays include 0.20 oz/t gold and 0.4 oz/t silver over 31.2 feet, 0.19 oz/t gold and 0.51 oz/t silver over 17.5 feet, and 3.31 oz/t gold and 3.2 oz/t silver over 1.4 feet (Peterson and others, 1982).
In 1986 Battle Mountain Exploration Company examined the vein systems and later mapped and sampled some of them. In 1990 they explored the area looking for large zones of argillic and silicic alteration having potential for disseminated gold mineralization. Argillically altered and silicified tuffs were found to be anomalous in arsenic and mercury and had spotty gold values as much as 0.025 parts per million (ppm) (Ellis and Apel, 1990).
In 2014 Redstar Gold Corp. collected approximately 150 soil and fine talus samples and over 50 rock samples covering the Aquila prospect (Redstar Gold Corp., 2014a). The soil and fine talus samples returned gold values ranging from 50 parts per billion (ppb) to 197 ppb and silver values from 0.5 grams per tonne (g/t) to 1.3 g/t. A rock sample from a narrow breccia vein with strong argillic alteration contained 90.2 g/t silver (Redstar Gold Corp., 2014b).
Redstar Gold Corp. conducted two phases of exploration in 2016 on their Unga project, which includes the Shumagin (PM064), Apollo (PM079; PM084), Centennial, Orange Mountain (PM067), Zachary Bay (PM054), Amethyst (PM092), and Aquila (PM086) epithermal gold-silver prospects. The Shumagin trend parallels the historically mined Apollo–Sitka vein system (PM079; PM084; PM076), which between 1886 and 1922 produced approximately 150,000 ounces of gold at a grade of approximately 0.292 ounce of gold per ton (Athey and Werdon, 2017).
In June 2016, Redstar Gold Corp.’s Phase I surface program included classifying alteration assemblages and conducting other geologic work to identify drill targets. From October through November, Phase II’s drilling program tested the down-dip and along-strike expansion potential of high-grade vein/breccia mineralization within the Shumigan Gold Zone (PM064). A total of 1,505 meters were drilled in 7 holes spaced over ~750 meters of strike length. All drill holes intersected the target structure, which includes multi-generational phreatomagmatic breccias, hydrothermal breccias, and late breccias and veins with colloform-crustiform- to cockade-textured quartz-adularia-carbonate (± rhodochrosite, ± green clay). Select intervals from drill holes 16SH019 and 16SH020 include 0.9 meter at 14.95 grams of gold per tonne and 1.15 meters at 11.3 grams of gold per tonne; release of full assay results is planned for late January 2017 (Athey and Werdon, 2017).
Indication of production None

Additional comments

The Aquila prospect lies land where the surface rights belong to the Unga Corporation and the subsurface rights belong to the Aleut Corporation (Redstar Gold Corp., 2015).