Emigrant Springs mine, Carlin Mining District, Elko County, Nevada, USAi

Regional Level Types
Emigrant Springs mine	Mine
Carlin Mining District	Mining District
Elko County	County
Nevada	State
USA	Country

Open pit heap leach operation started production in 2012.

The mine is expected to produce between 70,000 and 80,000 ounces of gold per year.

According to Newmont (2009), the undeveloped reserves at the Emigrant deposit consist of 1.2 million ounces of gold (37.3 t Au).
Structure: The 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.

Alteration: The 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.

Commodity: Ore Materials: gold Gangue Materials: barite, alunite, jarosite, kaolinite, limonite

Deposit: Emigrant is an oxide gold deposit exposed at the surface with a low strip ratio. Newmont?s current feasibility study assumes simple processing by run-of-mine heap leaching. The north-trending Emigrant fault zone hosts the Emigrant Springs deposit in mudstone of the Webb Formation along the contact of the Devils Gate Limestone.

Deposit type: Sediment-hosted Au

Development: For the portion of the deposit in section 26: Homestake Mining was the first to conduct exploration on the property. Activities in 1981 consisted of grid soil and rock chip sample surveys, and two outcropping gold-bearing jasperoid zones were tested with rotary drilling. Homestake terminated their lease and the property then passed to Tarpon Oil Company who drilled an additional 22 holes in 1983 and 1984. Western States Minerals Company optioned the property in 1985 and drilled 20 holes in an effort to expand the known mineralization. Teck Resources acquired the property in 1987 and conducted detailed geologic mapping, soil sampling, and IP geophysical surveys. 41 holes were drilled between 1987 and 1989, both to fill in the known mineralization and to test new targets. A total of 136 holes had been drilled by 1989. For the portion of the deposit in section 35: this portion of the deposit was discovered by Newmont in the early 1980s during exploration peripheral to the Rain deposit 1.5 miles to the west. In 2002, Newmont Mining Corp. continued to evaluate the Emigrant project on the Carlin trend, where they feel there is potential for expanding the old Emigrant Mine. The U.S. Bureau of Land Management has been working on an environmental assessment of a proposed project there for several years, and Emigrant is scheduled to be in production in 2008, with a 7 year mine life. In spring 2004 BLM publicized a notice that Newmont Mining Corporation has submitted a Plan of Operations to open the Emigrant Mine which would include developing and operating an open pit mine; constructing a waste rock disposal facility, storing oxide waste in mined areas of the pit; developing an oxide heap leach pad; and constructing ancillary facilities and concurrent reclamation. Proposed mining operations would last for approximately 9 years through the year 2013. In 2005, a reverse-circulation drilling program of more than 60 holes was aimed at delineating potential mineralization to the east of the defined Emigrant deposit.

Ore(s): The 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.


The deposit measures more than 2,130 meters in length (N-S), from 210 to 490 m in width (E-W), and from a few meters to as much as 75 meters thick.

Other Databases

Link to USGS MRDS:	10310411

Other Regions, Features and Areas containing this locality

References