Emigrant Deposit

Elko County, Nevada, United States

GoldArsenicAntimonyBarium-Barite

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Commodities

PrimaryGold

TertiaryArsenic, Antimony, Barium-Barite

Commodity typeB

Deposit

Deposit typeReplacement; sediment-hosted Au

Model173: Sediment-hosted Au

Deposit sizeN

Orebody formstratiform

Ore controlThe Emigrant Springs fault, a north-striking reverse fault is the conduit for gold-bearing hydrothermal fluids. Au occurs disseminated in jasperoid that has developed at and above the contact between massive limestones of the Devils Gate Formation and siliciclastic rocks of the overlying Webb Formation. This mineralized jasperoid forms a bedding parallel dip slope now exposed at surface, resulting in strip ratios of essentially 0:1. Proximity to the hinge of the Pinon Range anticline may have influenced localization of gold.

Materials

Ore mineralsGold

GangueBarite, Alunite, Jarosite, Kaolinite, Limonite

Geology

Host rockLimestone,Mudstone,Sandstone,Quartzite · "Devils Gate Limestone", "Webb Formation", "Chainman Formation"

Associated rockMonzonite

StructureThe Emigrant Springs fault is filled with jasperoidal breccia over a 50-foot width for 2200 feet along strike. The sense of movement on the fault is reverse., The property lies just beyond the easternmost limit of the Roberts Mountains Thrust. Emigrant Springs occurs on the NW limb of the Pinon Range anticline.

AlterationThe north-trending Emigrant fault zone hosts the Emigrant Springs deposit in mudstone of the Webb Formation along the contact of the Devils Gate Limestone. The Emigrant Springs fault is highly silicified with minor barite, alunite, jarosite, and kaolinite. The bedding parallel jasperoid which constitutes the ore zone is typically massive, waxy, tan to maroon, and fine-grained. Liesegang banding of unsilicified Webb Formation rocks above the jasperoid is common.

Economic & production

Development statusProspect

Discovery year1981

Identification

Deposit ID10310411

MRDS IDRE00037

Alternate namesEmigrant Springs Deposit

RegionNA

Data scoreB

Coordinates40.61741, -115.97341

References

NBMG MI-88 thru MI-02NBMG Bull. 106Elko Land Status Map 1978Amer. Mines (1996), 1995Thompson, 1999Newmont Ann. Rept. 1988Jackson, P., 1992, Geology and mineralization of the Emigrant Springs Project, Elko County, Nevada, in Buffa, R. and Coyner, A., eds., The Geology and Ore Deposits of the Great Basin-Field Trip Guidebook Compendium, The Geological Society of Nevada, Reno, p. 125-130.Thoreson, R., 1991, Geology and gold deposits of the Rain subdistrict, Elko County, Nevada, in Raines, G.L., et al., eds., Geology and Ore Deposits of the Great Basin, The Geological Society of Nevada, Reno, p. 635-643.Thoreson, R., 1990, Geology and Ore Deposits of the Rain Subdistrict, Elko County, Nevada, Oral Presentation at Great Basin Symposium, The Geological Society of Nevada, Reno/Sparks, April 4.Nevada Dept.of Minerals, 1994Newmont Gold 1993 Sec Form 10k;Jackson, 1991Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Significant deposits of gold, silver, copper, lead, and zinc in the United States: U.S. Geological Survey Open-File Report 90-206A, 33 p.; 98-206B. one 3.5 inch diskette.Adella Harding, Elko Daily Free Press, 10/4/02.Newmont 5-Year Business Plan Update (September 24, 2003) ? Supplemental Information.Anthony A. Longo, Tommy B. Thompson, and J. Bruce Harlan, 2002, Geologic Overview of the Rain Subdistrict, in NBMG Bull 111.