Mackie Gulch

Mine, Active

Commodities and mineralogy

Main commodities Au
Other commodities Ag
Ore minerals gold
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale ID
Quadrangle map, 1:63,360-scale D-1
Latitude 62.99036
Longitude -156.49474
Nearby scientific data Find additional scientific data near this location
Location and accuracy Mackie Gulch is a west-flowing stream that empties into Ganes Creek about 1 mile below the main Ganes Creek camp shown on the Iditarod D-2 topographic map. Mackie Gulch is not named on the USGS, D-1 topographic map but it flows across the SE1/4, section 33, T. 34N., R. 38W., Seward Meridian. The lower 1.2 miles mile is gold-bearing and the coordinates are at the mouth of the creek at an elevation of about 880 feet. The location is accurate. Mackie Gulch was described as locality 43 by Cobb (1972, [MF 363]).

Geologic setting

Geologic description

The rocks in the area of the Mackie Gulch Mine are shale, siltstone, and sandstone of the Upper Cretaceous, Kuskokwim Group. The sedimentary rocks are intruded by a Cretaceous to a Tertiary, mafic-to felsic swarm of dikes and sills near the Ganes-Yankee fault system (Bundtzen and Laird, 1983; Miller and Bundtzen, 1994). The placer gold is probably derived from the bimodal intrusive complex.
The pay streak is about 50 feet wide and is covered by from 13 to 50 feet of overburden. The pay streak extends for about 1.2 miles upstream from the mouth of the gulch. Placer gold was first recognized in Mackie Gulch shortly after discovery of gold on Ganes Creek in 1906 (Maddren, 1910). A total of at least 1,794 ounces of placer gold was mined from 1915 to 1938 and gold was produced intermittently from 1970 to 2001. The gold is about 940 fine. Some of the placer gold has adhering quartz.
Geologic map unit (-156.497103488811, 62.9897280839776)
Mineral deposit model Placer Au deposit (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Undated; probably Quaternary based on estimates of the age of the stream valley summarized in Bundtzen (1980 [GR 63]) and Bundtzen and Miller (1997).
Alteration of deposit None.

Production and reserves

Workings or exploration Placer gold was found in Mackie Gulch shortly after the Ganes Creek discovery in 1906 (Maddren, 1910). The deposit was mined from 1915 to 1938 (Mertie, 1936; Cobb, 1972, [MF 363]; Cobb, 1976 [OFR 76-576]). Mining began again in 1999 by the Clark-Wiltz partnership, who mined Mackie Gulch through the 2001 season. The workings extend from the mouth of the gulch upstream for a maximum distance of 1.2 miles. In the 1930s, a cut 15 by 50 feet in area exposed 5 feet of gravel covered by 12-16 inches of organic materials; i.e., there was almost no overburden (Mertie, 1936). As mined between 1999 to 2001, the placer cut was about 160 feet long and the overburden was up to 50 feet thick.
Indication of production Yes
Production notes From 1915 to 1938, Mackie Gulch produced 939 ounces of gold and 55 ounces of silver (Miller, Bundtzen, and Gray, 2005); it produced about 862 ounces of gold from 1970 to 2001 (T.K. Bundtzen, unpublished data, 2002). The total production is about 1,794 ounces of placer gold.

References

MRDS Number A015085

References

Reporters T.K. Bundtzen (Pacific Rim Geological Consulting, Inc.), M.L. Miller (U.S. Geological Survey); and C.C. Hawley (Hawley Resource Group)
Last report date 5/11/2003