Mine detail: Gold Acres Deposit

Previously called 'Little Gold AcresOld Kennecott GroupLime Point ClaimLakin ClaimMaloney ClaimLittle Squirt Claim'

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Location

Lat / long:

40.25213, -116.73982

Resource(M)

Primary:	Gold
Secondary:	Tungsten, Copper
Tertiary:	Antimony, Arsenic, Mercury, Thallium, Lead, Zinc, Molybdenum
Ore:	Gold, Molybdenite, Scheelite, Pyrite, Arsenopyrite, Sphalerite, Galena, Pyrrhotite
Orebody form:	tabular; stratabound
Discovery year:	1920

Production

Operation type:	Surface-Underground
Deposit type:	shear zone; breccia fill; sediment-hosted disseminated Au; epithermal
Production size:	Medium
Development status:	Producer
Production years:	1936-1961; 1973-1983; 1987-1996
First production started:	1935
Last production ended:	1996

Geology

Host rock:	Roberts Mountains Fm, Valmy Fm, Elder Sandstone
Host type:	Limestone,Chert,Shale,Sandstone,Porphyry
Associated type:	Quartz Monzonite
Structure:	Gold Acres is exposed at the western margin of the Gold Acres window along the NW-trending Roberts Mountains thrust, Cortez-Uinta axis. It lies along the Eureka-Battle Mountain trend of aligned deposits and mineralization., High angle normal faulting of various orientations has broken the mineralized zone into three parts: the main Gold Acres orebody, the Little Squirt orebody, and the Little Gold Acres orebody.
Tectonic:	geosyncine
Alteration processes:	Alteration of the deposit consists of carbonization, silicification, argillization, oxidation, and skarn formation. Carbonization (up to 3% by weight organic carbon) is the dominant alteration type in the deposit and can give a sooty appearance to the rocks. Silicification is strongest at the northern end of the deposit and decreases to the south. Argillization is primarily confined to fractures in lower plate carbonates associated with carbonization. The clays are generally illitic. Supergene oxidation is evident throughout the deposit area as limonitic and hematitic staining along fractures. Skarn development is associated with the emplacement of a Cretaceous granitic stock. Two prograde, skarn zones are developed, both barren of gold. A retrograde skarn alteration mineral assemblage consists of chlorite, tremolite, epidote, calcite, quartz, illite, nontronite, smithsonite(?), pyrite, pyrrhotite, chalcopyrite, sphalerite, arsenopyrite, and galena. Gold is not associated with the retrograde assemblage.

References

MRDS	W002496
MAS	320150008
DEP	10310461
Reference	{Deposit:: Ketner, K. B., 1965, Gold Acres Mine, in Gilluly, J., and Gates, O., Tectonic and Igneous Geology of the Northern Shoshone Range: USGS Professional Paper 465, p. 134-135}{Deposit:: Koschman, A. H., and Bergendahl, M. H., 1968, Principal Gold-Producing Districts of the United States: USGS Prof. Paper 610, p. 184}{Deposit:: Roberts, R. J., et al., 1971, Gold-Bearing Deposits in North-Central Nevada and Southwestern Idaho: Econ. Geol. 66 (1): 14-33}{Deposit:: Stager, H.K. (1977) Geology and Mineral Resources of Lander Co., Nevada; NBMG Bull 88}{Deposit:: Vanderburg, W. (1939) Reconnaissance of Mining Districts in Lander Co., Nevada; USBM I.C. 7043.}{Deposit:: Wrucke, C.T. (1974) Geologic Map of the Tenabo Area, Lander Co. Nevada, USGS Map Mf-647.}{Deposit:: Anctil, R.J. (1967) Gold Acres Project, Report prepared for Union Pacific Land Co.}{Deposit:: USBM (Winnemucca) MILS No. 54, Ref. No. 3201500052, Mineral Property File 74.500}{Deposit:: The Nevada Mineral Industry 1990; NBMG Special Publication MI-1990, P.22.}{Deposit:: Hays, R.C., and Foo, S.T., 1991, Geology and Mineralization of the Gold Acres Deposit Lander County, Nevada, in Raines, G.L., Lisle, R.E., Schafer, R.W. and Wilkinson, W.H., Eds., Symposium Proceedings, Geology and Ore Deposits of the Great Basin, Geologic Society of Nevada and the U.S. Geological Survey, April 1-5, 1990, p. 677-685.}{Deposit:: McCormack, John, 1991, Written comments on record, 18 Oct/91.}{Deposit:: NBMG, MI-83; MI-84; MI-86 thru MI-96; MI-02.}{Deposit:: Long, 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.}{Deposit:: NBMG Map 91, 1st, 2nd, 3rd}{Deposit:: Amer. Mines (1989), 1989 thru Amer. Mines (2001), 2000}{Deposit:: MASMILS 0320150008, 0320150626}{Deposit:: Crescent Valley Land Status, 1979}{Deposit:: NBMG Bull. 38.}{Deposit:: Adella Harding, Elko Daily Free Press Mining Quarterly, Winter 2002-2003.}
Reporter	LaPointe, D.D. , Schruben, Paul G.