Homestake Mine, Lead, Lead Mining District, Lawrence County, South Dakota, USAi

Regional Level Types
Homestake Mine	Mine
Lead	- not defined -
Lead Mining District	Mining District
Lawrence County	County
South Dakota	State
USA	Country

A recently closed major Au-Ag mine located in sec. 33, T5N, R3E, BHM, 0.8 km (0.5 miles) NE of Lead (city hall). Discovered in 1875 by Moses Manuel and Frank Harney. The original claim was filed in April 1876. Owned by the Homestake Mining Co. Closed in 2002. MRDS database stated accuracy for this location is 10 meters. This mine is very evident on the topo maps.

Alternate names which apply to this property include: Black Hills Consolidated Mines; Yates shaft; Calhoon Mill; Homestake Cyanide Mill No. 1; Homestake & Open Cut; Ellison shaft; Homestake Cyanide; Deadwood Mill; Highland Mill; Ross shaft; Oro Hondo shaft; Old Abe shaft; Homestake slime plant; De Smet Mill; Terra Mill; Hidden Fortune Mining Co.; Homestake Mill; Golden Star Mill; Homestake Extension shaft; and the Columbus Consolidated Gold Mining Co.

Mineralization is Neoproterozoic in age. The ore bodies are irregular, pipe-like structures. Controls for ore emplacement included 1.) a sulfide-bearing phase of the Homestake Formation; 2.) cross folds; and, 3.) proximity to garnet isograd...

Ore body No. 1: Pipes and lenses; plunge:40°; depth-to-bottom: 2,438.4 meters; width: 30.48 meters; length: 121.92 meters. It strikes N40E and dips 60S. The depth-to-top is 1,525 meters.

Second ore body: It is a shear zone body that is tabular in shape, strikes N10E, dips 70W, with a depth-to-top of 185 meters and a length of 1,350 meters. The primary mode of origin is hydrothermal. Primary ore control was lithology. Wall rock alteration is moderate (propylitic, silicification, and pyritization). Controls for ore emplacement include tightly folded plunging anticlines and synclines. Local rocks include sedimentary Iron Formation. Geologic units near the site include metamorphosed carbonaceous shale, the Whitewood Limestone, Winnipeg Formation, and Deadwood Formation.

Ore from the Homestake usually consists of masses of chlorite and quartz with leaves, rods or irregular masses of free gold attached, which is seldom more than 2 cm in largest dimension and usually much smaller. Exceptional specimens consisting of well-developed arsenopyrite crystals enclosing or encrusted with native gold, and occasional octahedral crystals of gold up to 2 mm in size have been collected.

Associated rocks include Pliocene-Neoproterozoic syenite; rhyolite; granite, granite porphyry, cutting stock; rhyolite & syenite dikes; amphibolite, irregular intrusives.

Regional geological structures include the Black Hills.

Local structures: Local subsidiary domes; the Lead syncline. The rocks are in a set of large isoclinal folds that have been refolded by two sets of smaller folds, which result in extremely complex configurations. Also, warping is caused by Tertiary igneous rocks and the dome formed around the cutting stock, which is exposed West of Lead. The ore bodies are located in the younger set of crossfolds.

Workings include surface and underground openings and achieved a depth of at least 2,300 meters. The depth in 1968 was 2073 meters.

Produced 1.7 million tons of ore in 1984 (9,200 kg Au).

Analytical data results: Native Au contains an average of 17% Ag, 1% Cu and other metals.

Resource/reserves data: Year: 1997: total resources 43,555,000 metric tons ore at 6.320000 grams/metric ton Au.

The Homestake mine was the site for the Davis experiment in which Raymond Davis, Jr. made the first direct measurement of solar neutrinos. Preparations began in the late 1960s and the experiment ran from 1970 to 1994. (Wikipedia, Homestake Experiment)

At the time the mine closed in 2002 it was under consideration by the National Science Foundation (NSF) as a site for the United States’ Deep Underground Science and Engineering Laboratory (DUSEL). Negotiations took longer than Barrick Gold was willing to bear the expense of keeping the inactive mine dewatered, so the pumps were turned off in 2003 and the mine flooded.

In 2007 the Sanford Underground Research Facility (SURF) was established, named in recognition of a $70 million founding donation by T. Denny Sanford. The mine was dewatered to allow development of new DUSEL laboratories on the 4850-foot level, some of which occupy the cavern excavated for the Davis experiment in the 1960s. A state-of-the-art water treatment plant processes output from ongoing dewatering to make it safe to discharge into a surface stream at the site. (Wikipedia, Sanford Underground Research Facility)

Olson (2019) is an account of recent underground construction for the labs, and Broberg (2021) is a detailed history of the huge Nordberg hoists at the Ross shaft which still service the labs today. More information about current shaft operations can be found at https://sanfordlab.org/facility .

Other Databases

Wikipedia:	https://en.wikipedia.org/wiki/Homestake_Mine_(South_Dakota)
Wikidata ID:	Q2351504
Link to USGS MRDS:	10069099

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