Mine detail: McMahon Ridge

Previously called ''

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Location

Lat / long:

37.71023, -117.23341

Resource(B)

Primary:	Gold
Secondary:	Silver, Copper, Lead
Tertiary:	Bismuth, Potassium, Antimony, Tin
Ore:	Gold
Gangue:	Quartz, Alunite, Barite, Gypsum, Limonite, Kaolin
Orebody form:	Irregular to tabular or knobby
Discovery year:	1902

Production

Operation type:	Surface-Underground
Deposit type:	silicified zones at shear intersections
Production size:	Yes
Development status:	Producer
Production years:	1904-1970s
First production started:	1904
Last production ended:	1970

Geology

Host rock:	Milltown andesite
Host type:	Rhyodacite,Andesite
Structure:	The most productive mines in Goldfield form an arcuate belt that trends generally north from the Goldfield Main District, then northeast through the Adams and Conqueror mines area, and then easterly through McMahon Ridge and Black Butte. This belt of gold deposits coincides with the western and northern limits of an inferred intrusive-related, ring-fracture system and is host to nearly all of the most productive gold ore bodies known in the District., Tertiary deposits are domed and faulted by steeply dipping post Miocene: N-S and E-W faults.
Tectonic:	volcanic center, Basin and Range
Alteration processes:	Large envelopes of intense argillic alteration surround most of the ore zones with silicification of core ore zones.

References

MRDS	W002900
DEP	10310418
Reference	{Deposit:: Ransome, F. L. 1909, Geol. and Ore Deposits of Goldfield, Nev.: USGS Prof. Paper 66, 258 p.}{Deposit:: Searls, F. Jr., 1948, Geol and Ore Deposits of Goldfield, Nev.: Nevada Univ. Bull., v.42, no. 5, Geology and Mining Ser. 48, 24 p.}{Deposit:: Koschmann, A. H. and Bergendahl, M. H., 1968; Principal Gold Producing Districts of the United States: USGS Prof. Paper 610}{Deposit:: Spurr, J E, 1905, The Ores of Goldfield, Nev.: USGS Bull. No. 260, p. 132-139.}{Deposit:: Lincoln, F C, 1923, Mining Dist and Min. Res. Nev.: Reno, Nev. Newsletter Pub., p. 67-73}{Deposit:: Albers, J.P. and Stewart, J.H., 1972, Geology and Mineral Deposits of Esmeralda County, Nevada: NBMG Bull. 78, p. 67-69}{Deposit:: Steven Ristorcelli, Scott Hardy, and Neil Prenn, 2003, Geology and Mineralization of the Goldfield Area, Esmeralda,County, Nevada; Geological Society of Nevada Special Publication No. 37: Spring 2003 Field Trip Guidebook Gold Deposits of the Goldfield, Midway and Thunder Mountain Areas}{Deposit:: Internet website for Metallic Ventures Inc.}{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 MI-80 through MI-99}{Deposit:: NBMG Map 91 1st, 2nd, 3rd}{Deposit:: MAS, 1984}{Deposit:: Amer. Mines (1990-2001)}{Deposit:: NBMG Bull 78}{Deposit:: www.romarco.com}{Deposit:: Metallic Ventures Inc., press release, 12/23/02.}
Reporter	LaPointe, D. D., Schruben, Paul G.