Getchell Gold Mine

Humboldt County, Nevada, United States

GoldSilverArsenicBarium-BariteMolybdenumFluorine-FluoriteThalliumTelluriumBismuthTinLeadZincCopperTungstenAntimonyMercury

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Description

Edward Knight and Emmet Chase

Commodities

PrimaryGold, Silver

SecondaryArsenic

TertiaryBarium-Barite, Molybdenum, Fluorine-Fluorite, Thallium, Tellurium, Bismuth, Tin, Lead, Zinc, Copper, Tungsten, Antimony, Mercury

Commodity typeB

Deposit

Deposit typeReplacement

Model173: Sediment-hosted Au

Deposit sizeM

Orebody formIndividual orebodies are roughly tabular

Ore controlEconomic amounts of gold are restricted to tabular sheet-like zones (termed "veins" by Joralemon) within the Getchell fault zone and within favorable calcareous lithologies.

Materials

Ore mineralsGold, Silver, Electrum, Orpiment, Pyrite, Scheelite, Pyrrhotite, Arsenopyrite, Marcasite, Magnetite, Stibnite, Ilsemannite, Cinnabar, Hubnerite, Calcite, Chabazite, Sericite, Chlorite, Barite, Gypsum, Fluorite, Getchellite, Galkhaite, Laffittite, Arsenolite, Guerinite, Haidingerite, Pharmacolite, Weilite, Coloradoite, Bismuthinite, Cassiterite, Molybdenite, Ferrimolybdite, Galena, Sphalerite, Covellite, Chalcocite, Garnet, Epidote

GangueRealgar

Geology

Host rockShale,Limestone · Preble Formation

Associated rockGranodiorite,Porphyry · Osgood Mountains pluton

Structurethrust faults to the north and NNW-trending faults., Gold mineralization is generally found at the intersection of a number of high-angle and low-angle fault sets. The low-angle faults and associated folds are the result of Devonian and Permian-age compressional events and the higher angle faults and fracture sets formed during Tertiary extension. Mineralization is both structurally and stratigraphically controlled. \nThe Getchell fault is a zone of overlapping fractures which have an overall strike of N10W. Hotz and Willden (1964) offer evidence for up to 3500 feet of left lateral strike slip displacement and only a relatively small amount of dip slip movement along the Getchell fault. McCollum and McCollum (1991) indicate that the sense of movement on the Getchell fault is right lateral. The Getchell Fault Zone is a complex system of sub-parallel, high angle faults which is at least 500 m wide. The zone is made up of a number of fault planes, separated by brecciated gouge and characterised by intense clay alteration, and by brecciation in the hangingwall. , The main Getchell deposit within the fault has been drilled to a depth of 600 m down dip from the original surface, and remains open down dip. There is a 'Main Vein' which is a dominant structure with a distinct footwall, complexed by several conjugate veins to the west. Sub-parallel, mineralised structures have also been found up to 200 m into the footwall of this main structure, while alteration, fault gouge and mineralisation occur up to 500 m to the east into its hangingwall (FirstMiss Gold Inc., 1993). Movement on the Getchell Fault has been both normal and dextral strike-slip (McCollum & McCollum 1990). On the basis of the relative displacement of the Palaeozoic sediments and the Cretaceous granodiorite of the Osgood Mountain Stock it is believed that the Getchell Fault is a reactivated older structure (D Bond, Pers. comm., 1993). The most recent displacement has taken place during the Miocene to present Basin and Range movement, representing further reactivation of an older structure. The fault cuts all three main stratigraphic units found within the pit, as well as the Osgood Mountain Stock. Altered blocks of granodiorite, rimmed by the skarn assemblage, are faulted downwards along the footwall structure into the Getchell Fault Zone and subsequently mineralised with gold (FirstMiss Gold Inc., 1993).\n

AlterationAlteration comments: there is a metamorphic aureole around the Osgood Mountains granodiorite which has produced in the surrounding shaly rocks a mineral assemblage consisting of cordierite-, biotite-, and andalusite-hornfels. Locally limy beds are recrystallized and calc-silicate minerals are developed. Hydrothermal alteration consists chiefly of decarbonatization accompanied by silicification in the limestone beds. Cordierite, andalusite, and biotite of the metamorphic aureole are altered to sericite and/or chlorite. Igneous dikes and portions of the main stock are altered such that plagioclase is altered to sericite and kaolinite and biotite is altered to sericite, chlorite, and pyrite.

Economic & production

Development statusProducer

Production years1938-1945; 1948-1950; 1962-1967; 1985-1999

First production1938

Last production1999

Discovery year1933

Identification

Deposit ID10310488

MRDS IDM055410

Alternate namesNorth Pit, Center pit, South pit

RegionNA

Data scoreA

Coordinates41.2079, -117.2513

References

McCollum, L. B. and McCollum, M., 1991, Paleozoic rocks of the Osgood Mountains, Nevada, in Raines, G. L., et al, eds., Geology and Ore Deposits of the Great Basin, The Geological Society of Nevada, Reno, p. 735-738.Bagby, W. C. and Cline, J. S., 1991, Constraints on the pressure of formation of the Getchell gold deposit, Humboldt County, Nevada, as interpreted from secondary-fluid-inclusion data, in Raines, G. L., et al, eds., Geology and Ore Deposits of the Great Basin, The Geological Society of Nevada, Reno, p. 793-804.Madden-McGuire, D. J., 1991, Stratigraphy of the limestone-bearing part of the lower Cambrian to lower Ordovician Preble Formation near its type locality, Humboldt County, North Central Nevada, in Raines, G. L., et al, eds., Geology and Ore Deposits of the Great Basin, The Geological Society of Nevada, Reno, p. 875-893.Berger, B. R. and Tingley, J. V., 1985, History of discovery, mining, exploration of the Getchell mine, Humboldt County, Nevada, in Hollister, V. F., ed., Discoveries of epithermal precious metal deposits, case histories of mineral discoveries vol. 1, Society of Mining Engineers, New York, P. 49-51.Berger, B. R., 1985 Geological and geochemical relationships at the Getchell Mine and vicinity, Humboldt County, Nevada, in Hollister, V. F., ed., Discoveries of epithermal precious metal deposits, case histories of mineral discoveries vol. 1, Society of Mining Engineers, New York, p. 51-59.Dunning, Gail E., 1988, calcium arsenate minerals new to the Getchell Mine, Nevada, The Mineralogical Record, Vol. 19, No. 4, p. 253-257.Erickson, R. L., Marranzino, A. P., Oda-Uteana, and Janes, W. W., 1964, Geochemical exploration near the Getchell Mine, Humboldt County, Nevada, USGS Bulletin 1198-A, 26 pp.Hardy, R. A., 1940 Geology of the Getchell Mine, AIME Technical Publication No. 1240, 3 Pp.Wise, F. and Wark, C. W., 1940, Metallurgy and milling practice at Getchell Mine, AIME Technical Publication 1260, 9 Pp.First Mississippi Corp., Annual Reports for fiscal years 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991.NBMG, 1994, MI-1993Nevada Division of Minerals, 1994Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Database of significant deposits of gold, silver, copper, lead, and zinc in the United States; Part A, Database description and analysis; part B, Digital database: U.S. Geological Survey Open-File Report 98-206, 33 p., one 3.5 inch diskette.Getchell - Internet report by Porter Geoconsultancy.Placer Dome Gold Company website, 2003.