Lucky Shot

Mine, Active

Alternative names

Willow Creek Mines Inc.

Commodities and mineralogy

Main commodities Au
Other commodities As; Cu; Pb; Sb; Te; Zn
Ore minerals arsenopyrite; chalcopyrite; galena; gold; pyrite; sphalerite; stibnite; tellurides; tetrahedrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale AN
Quadrangle map, 1:63,360-scale D-7
Latitude 61.779
Longitude -149.4078
Nearby scientific data Find additional scientific data near this location
Location and accuracy The portal of the Lucky Shot Mine is on the northwest valley wall of Craigie Creek, 1.8 miles northeast of the junction of Craigie Creek and Willow Creek. The mine is marked by a symbol labeled 'Lucky Shot Mine' on the Anchorage D-7 1:63,360-scale topographic map. It is near the center of section 35, T. 20 N., R. 1 W. of the Seward Meridian. The underground workings and exploration activities extend far beyond the the portal. The adjacent War Baby Mine (AN003) and the Lucky Shot Mine were long ago consolidated into a single property which now is commonly referred to as the Lucky Shot.

Geologic setting

Geologic description

The Lucky Shot Mine consists of 4 blocks - the Coleman, Lucky Shot, War Baby, and Murphy blocks. In the early days of the district, these were more or less contiguous if somewhat separate properties at least in name but they are being explored and developed as a single property (Full Metal Minerals, 2010a; Stevens, 2010). The deposit consists of quartz veins along shear zones that cut the Late Cretaceous Willow Creek Pluton, which is jointed and sheeted near the surface but less so underground. The pluton is zoned; the outer part consists of hornblende quartz diorite and lesser hornblende tonalite; the core consists of hornblende-biotite granodiorite and lesser hornblende-biotite quartz monzodiorite and biotite quartz monzonite.
The classic mesothermal quartz veins at the Lucky Shot occur along shear zones that exhibit both ductile and brittle properties; the shear zones are up to 100 feet wide. The veins are between two major northeastward-dipping transverse faults. The quartz veins that were mined prior to WWII were generally 2 to 4 feet wide; they strike about N 80 E, and dip about 40 N. Post mineral faults offset the veins up to 800 feet and the quartz in the veins often is fractured. There are two generations of quartz veins. An older group is generally parallel to southwest-dipping joints in the pluton. These veins contain three different suites of ore minerals: 1) chalcopyrite, pyrite, and arsenopyrite; 2) pyrite and stibnite; and 3) sparse pyrite, sphalerite, and minor gold. The younger and economically important veins occur along the major shear zones. Pyrite is the most common ore mineral in them; arsenopyrite and galena are often present; scheelite is locally present; and there are trace tellurides including nagyagite, altaite, and possibly coloradoite. The wall rocks are intensely altered near the veins. Adjacent to the veins, the wall rock is bleached white or gray-green with much sericite, clay, and carbonates. There is an outer zone of propylitic alteration. There are two periods of mineralization, 66 Ma and 55 to 57 Ma (Madden-McGuire and others, 1988; Harlan, 2003). Fluid inclusion studies and isotope geochemistry indicate that the temperature of the ore forming fluids was 300 to 325 degrees (Burleigh, 1987, Silberman and others, 1978).
During the mining before WWII, the stopes along the vein averaged about 5 feet thick, the grade of the ore was typically a half ounce to two ounces per ton and the workings only went down to 500 feet or less below the surface (Stevens, 2010). The work since 2005 has revealed that there are much wider mineralization, even if at lower grade, and that the mineralization extends well below and beyond the old workings. The mineralization at the Lucky Shot has been traced for more than 4,000 meters horizontally, has a vertical extent of at least a thousand meters and has an average width of about 400 meters (Stevens, 2010). Over the last half century or more there have been several estimates of the gold resources of the Lucky Shot Mine. Most are now of little more than historic interest in view of the recent exploration. A resource estimate on the Coleman Zone was completed by Miranda Gold Corp. in September 2014 (Linebarger, 2014).
In March 2016, Miranda and Gold Torrent announced an updated resource estimate for the Willow Creek project, including measured and indicated resources of 121,500 ounces of gold averaging 18.3 grams of gold per tonne and 12,100 ounces of silver averaging 1.8 grams of silver per tonne contained in 206,600 tonnes of material. Inferred mineral resources include 59,000 tonnes of material that contain 35,150 ounces of gold averaging18.5 grams of gold per tonne and 2,900 ounces of silver averaging 1.5 grams of silver per tonne (Black and others, 2016a).
Geologic map unit (-149.410017626319, 61.7784724224795)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Late Cretaceous or younger (66 Ma and 55 to 57 Ma); veins cut the Late Cretaceous Willow Creek Pluton (Madden-McGuire and others, 1988; Harlan, 2003).
Alteration of deposit The wall rocks are intensely altered near the veins. Adjacent to the veins, the wall rock is bleached white or gray-green, with much sericite, clay, and carbonates. There is an outer zone of propylitic alteration (Madden-McGuire and others, 1988; Harlan, 2003).

Production and reserves

Workings or exploration Gold was discovered in the Lucky Shot area in 1918 and mining began in 1922 (Stoll, 1997, is a detailed history of the mining at the Lucky Shot and other mines in the Willow Creek district.). Mining continued fairly regularly until 1942; the mine did not reopen after WWII. Ensearch Exploration Inc. obtained the property in 1979 and did considerable underground work and exploration drilling. A 100-ton-a-day mill was built and about 10,000 tons of ore was milled. Several companies continued exploration into the early 1990s and another 1,000 tons of ore was mined. In 2005, Full Metals Minerals Corp. began intensive exploration of the Lucky Shot (Full Metal Minerals Corp., 2010a). Through 2008, Full Metal Minerals diamond drilled 164 holes; sampled the old dumps and underground workings; rehabilitated, improved, and sampled the old underground workings; and mined a bulk sample for metallurgical testing. In 2009, they drilled another 27 holes with several notable intercepts with 24.14 to 102.00 grams of gold per tonne (Full Metal Minerals Corp., 2010b). In the late Fall of 2009, they finalized an option agreement with Harmony Gold Corporation to continue exploring the property (Full Metal Minerals Corp., 2009). In November 2013, Miranda Gold Corp. (Miranda) entered a lease agreement with Alaska Hardrock Inc. and the following year Miranda completed a resource estimate on the Coleman Zone (Linebarger, 2014).
Indication of production Yes; medium
Reserve estimates
A National Instrument 43-101 compliant resource estimate on the Coleman Zone was completed by Miranda Gold Corp. in September 2014. The resource was calculated using a 7 gram per tonne gold cutoff grade. The measured resource was calculated to be 11,500 tonnes at 28.5 grams per tonne gold, yielding 10,500 troy ounces. The indicated resource was calculated to be 67,200 tonnes at 23.9 grams per tonne gold, yielding 51,600 troy ounces. The inferred resource was calculated to be 5,300 tonnes at 24.2 grams per tonne gold, yielding 4,100 troy ounces (Linebarger, 2014).
In March 2016, Miranda and Gold Torrent announced an updated resource estimate for the Willow Creek project, including measured and indicated resources of 121,500 ounces of gold averaging 18.3 grams of gold per tonne and 12,100 ounces of silver averaging 1.8 grams of silver per tonne contained in 206,600 tonnes of material. Inferred mineral resources include 59,000 tonnes of material that contain 35,150 ounces of gold averaging18.5 grams of gold per tonne and 2,900 ounces of silver averaging 1.5 grams of silver per tonne (Black and others, 2016a). All estimated resources are based on a cutoff grade of 5.0 grams of gold per tonne, a long-term gold price of $1,265 per ounce, and assumed metallurgical recoveries of 80 percent. Improved understanding of the geologic controls on mineralization resulted in a significant increase in the mineral-resource estimate for the Willow Creek project. In total, mineral resources at the Willow Creek project include eight veins in the Coleman area and two veins in the Lucky Shot area (AN002), and are based on information from 174 drill holes. Potential exists to increase the mineral resources through drilling down-dip extensions of the Coleman and Lucky Shot area, and the exploration targets in the War Baby (AN 003) and Murphy areas along strike to the east (Athey and Werdon, 2017). In July 2016, a newly completed NI 43-101 preliminary feasibility study reported proven and probable mineral reserves of 93,274 ounces of gold contained in 207,000 tonnes of material grading an average of 14.0 grams of gold per tonne (Black and others, 2016b).
The Willow Creek project is currently being developed through a joint-venture partnership between Miranda Gold Corp. and Gold Torrent Inc., with Gold Torrent currently earning a 70 percent equity interest through the funding of the first $10 million in development costs (Athey and Werdon, 2017).
Production notes The Lucky Shot Mine and the adjacent War Baby Mine (AN003) were combined prior to WWII and both mines were simultaneously operated by Willow Creek Mines. Stoll (1997) estimated that the total production to 1951 from the combined mines was about 252,000 ounces of gold.

References

MRDS Number A011601

References

Burleigh, R.E., 1987, A Stable Isotope, Fluid Inclusion and Ore Petrographic Study of the Gold Quartz Veins in the Willow Creek Mining District. Masters Thesis, University of Alaska.
Reporters D.P. Bickerstaff (USGS); S.W. Huss (USGS); D.J. Grybeck (Contractor, U.S. Geological Survey); N.V. King (Alaska Earth Sciences); M.B. Werdon (DGGS)
Last report date 8/26/2017