Thacker Pass, Nevada

THE RECENTLY APPROVED (2/20/2020) Sierra Club policy “Mining and Mining Law Reform Policy (including minerals for Clean Energy)” states in its opening sentences:

Mining by its very nature is a dirty business and highly disruptive of the nat­ural and human environment. It involves disturbing the terrestrial and/or marine environment with short term and long term negative impacts from all phases including exploration, development, min­ing, milling, waste disposal, upgrading, transportation, and post-mining land use.

It later states:

Minerals and metals needed for the transition to 100% clean renewable energy worldwide and ultimately zero net carbon need to meet these same high standards [e.g., Initiative for Responsible Mining Assurance1] and there should be no waiving of standards to provide these minerals and metals.

Lithium is mentioned twice in this Sierra Club (hereafter “Club”) policy, and it is no secret that the Club has been one of the most aggressive non-profit organi­zations in seeking the energy transition that will take us away from fossil fuels. Nearly everyone agrees that lithium bat­teries will be an essential ingredient in that transition, primarily to fuel vehicles and to provide energy storage at sites of renewable (but inconstant) energy generation.

Lithium is number three on the periodic table, preceded by hydrogen and helium. It is also the first metal on the periodic table and is highly reac­tive, meaning it combines with other elements readily to create compounds. In fact, lithium is simply not found in pure form in the Earth. It is rare and comprises only about 0.002 percent of the Earth’s crust by weight, at concentra­tions of 20-70 ppm (parts per million). It is most often found as lithium carbonate (Li2CO3) or lithium hydroxide (LiOH). What makes lithium ideal for batteries is the combination of its low weight and its ability to readily give up an electron in becoming an ion – thus the name “lithium ion battery.”

So where do we get lithium? The US has only one lithium mine, located in Clayton Valley, Esmeralda County, Nevada. Called the Silver Peak Mine, it is operated by Albemarle Corp.2 which has lithium sites around the world. The Silver Peak Mine is decades old, having started in the 1960s when lithium was assayed from silver-producing claims. Until recently the mine produced lith­ium for various uses such as lithium soaps and greases, chemical reactions, tritium production, and pharmaceuti­cals. As lithium mining has increased around the globe, the mine has seen its contribution to the world’s lithium pro­duction shrink to 5% or less. The future of the Silver Peak Mine is uncertain due to economic viability and water availability, but recently Albemarle announced plans to double production.

General location of the Thacker Pass lithium mine within the 17-million-year-old McDermitt Caldera of north-central Nevada.

General location of the Thacker Pass lithium mine
within the 17-million-year-old
McDermittCaldera of north-central Nevada.

But the future of lithium mining in Nevada appears certain. The Nevada Division of Minerals states on its website of placer mineral claims in Nevada3 that “As of February 6, 2020 an estimated 7,996 active placer claims, assessment year 2020, have been located in Nevada, presumably for lithium brine in eigh­teen different hydrographic basins.”

The words “lithium brine” should cause great concern, since the Silver Peak Mine uses an evaporative method to concentrate its lithium from pumped brines. The mine consequently has a very large footprint in Clayton Valley when viewed from space (Figure 1). Our barren Nevada playas are a landscape feature of great reverence, with the Black Rock Desert playa in northwest Nevada the focus of a National Conser­vation Area where the famous Burning Man Festival occurs annually. How many playas are we willing to sacrifice to lithium brine evaporation pools?

Enter the Thacker Pass lithium mine in north-central Nevada, a pros­pect owned by Lithium Americas Corp. It has recently gone through the NEPA4 process to describe environmental impacts. This proposed mine sits in the McDermitt Caldera, a geologic feature that anchors the southwestern end of a series of calderas which spread north­eastward to Yellowstone National Park over the past 17 million years. Figure 2 is a basemap of the current topogra­phy of the caldera, with Thacker Pass indicated in the lower part. Within the caldera, lithium was spewed out with other minerals in enormous volcanic eruptions, forming a rim. This rim was subsequently eroded inward to form thick sedimentary sequences with espe­cially high lithium content. The defining character of McDermitt Caldera is that it remained a contained basin for a long period, much as the entire Great Basin has remained an inland basin with no drainage to the outside. Eventually the caldera was eroded such that it now drains to the outside. But the contained period was long enough to ensure that thick lithium-bearing deposits exist, with concentrations up to 100 times greater than in the Earth’s crust in general.

At first glance, the proposed Thack­er Pass lithium mine appears to have much less environmental impact than the Silver Peak lithium mine. This pri­marily is due to the fact that the lithium will be mined from a pit and processed as an ore into lithium carbonate, some­what like typical gold mines in Nevada. This sounds ominous, but let’s compare Thacker Pass to the existing Silver Peak lithium mine.

The lithium carbonate extracted from ore at Thacker Pass may have lithi­um concentrations of 2000 ppm or great­er, or roughly two orders of magnitude greater than background concentrations in the Earth’s crust. (Compare 2000 ppm for lithium with the fact that gold ore is considered “high-grade” beginning at 8 ppm, a factor of 250 less concentrated.) At Thacker Pass, a process which relies on sulfuric acid to concentrate the lithi­um out of the crushed ore will take place within an enclosed structure of relative­ly small footprint compared to evapora­tion ponds at the Silver Peak mine.

In its 2018 feasibility study5, Lithi­um Americas estimated that the Thacker Pass mine could produce 30,000 tonnes annually of lithium carbonate equiva­lent (LCE) in Phase I and 60,000 in Phase II. These figures have been repeated in the recent NEPA documents. In contrast, the Silver Peak mine had a production of approximately 5,000 tonnes of LCE in 2019, or about 1.5% of total world pro­duction in that year. The land area taken up by evaporation ponds in Figure 1 for the Silver Peak mine can be roughly estimated in Google Earth as 35 sq. mi. In the NEPA documents on Thacker Pass mine, the mine plan acreage is given as roughly 16 sq. mi., much of which will not actually be disturbed. Adjusted for production rate, the Thacker Pass mine will produce 10-20 times more LCE than the Silver Peak mine per square mile of project area. The favorability of placer-ore mining of lithium over brine mining seems quite evident.

In addition, the consumptive water use of the two methods favors the placer production. In the NEPA documents, one sees that the Thacker Pass mine will consume approximately 5,200 acre-feet per year. The Silver Peak mine pumps about 12,000 acre-feet of water annually 6 while producing much less lithium, as noted above. (It may be assumed that all the pumped brine water is lost in the evaporation process.)

A Google Earth view of Clayton Valley and the Silver Peak lithium mine. Pumped brine is flooded into evaporation ponds to concentrate the lithium product.

A Google Earth view of Clayton Valley and the Silver Peak lithium mine.
Pumped brine is flooded into evaporation ponds to concentrate the lithium product.

In early 2020, we were alerted that a draft Environmental Impact State­ment (EIS) would be soon prepared for the Thacker Pass mine. An accelerated schedule was put forth by the Bureau of Land Management (BLM), with rushed public meetings that were further neu­tralized by remote participation forced by the coronavirus pandemic. The Toiy­abe Chapter signed onto a May 15, 2020, letter to the BLM asking that the scoping comment period be extended and that the draft EIS not be released sooner than July 1. BLM responded positively to the latter request, and Lithium Americas re­leased its draft EIS on July 29, 2020. But the short 45-day comment period on the draft EIS was to conclude on September 14, 2020, so again this was protested on the basis of it being too short during the pandemic. This time the protest was to no avail. Lithium Americas released the final EIS on December 4, 2020. A Record of Decision approving the mine plan was issued by the BLM on 1/15/2021.

The Toiyabe Chapter submitted a 12-page comment letter on the draft EIS. We did not, however, join in the very detailed 71-page comment letter submit­ted by several parties led by Great Basin Resource Watch (GBRW). This was done in order to maintain our independence on this mine issue. We were also quite aware of the nexus between Club strat­egy on the energy transition and this first lithium mine in the US to follow the lone producing Silver Peak mine. There were important issues with the EIS that we and GBRW wished to see addressed. Among others, these include amount of water use, wildlife displacement (espe­cially the greater sage-grouse), threats to springs, and greenhouse gas (GHG) emissions.

The GHG emissions are of interest because Lithium Americas touts the project as “carbon-neutral.” It is not as a whole. They will attempt to be carbon neutral at the sulfuric-acid plant (which will create electrical power using heat generated in a continuous reaction), but have ignored GHG emissions from the haulage of LCE out, the haulage of various supplies in, the mining of the pit, and the miscellaneous other uses of fossil fuels. In fact, their own estimate in the Final EIS (Appendix B, Table 3.9) is 26,000 gallons per day average of diesel fuel for the total of mine operations. On a yearly basis, this amounts to 9.5M gal­lons. Using Energy Information Agency7 figures for overall consumption of pe­troleum in Nevada, this mine would be responsible for 0.41% of Nevada’s entire annual consumption. This is substantial. We have no comparison figures for the Silver Peak mine, but assume it is much less there because (1) the sun does the evaporative work to concentrate the lith­ium, and (2) pumping brine is much less energy-intensive than mining ore. Such a comparison will be important to make in the future when energy use estimates can be obtained for the Silver Peak mine.

The Toiyabe Chapter position on the Thacker Pass mine has remained neutral during the NEPA process. This stance was approved by the Club’s Vice-Pres­ident for Conservation and by leaders of the Program Department. Although there are clearly impacts with this mine plan, there are several reasons the Club has chosen not to oppose. The chapter has, for some years, depended on GBRW (formerly Great Basin Mine Watch) to deal with the glut of environmental issues related to mining. And we are mindful that there are many hurdles that the Thacker Pass lithium mine must pass in addition to the EIS. These hur­dles are in the form of permits managed by the Nevada Department of Environ­mental Protection, the State Engineer (water), and of course the BLM. There are opportunities for public involvement at all these hurdles, and we shall be vigilant.

The Club has already felt the sting of promoting renewable energy and the con­sequent issues arising from large-scale solar and wind farms. This is a difficult path to navigate. Now, with the need to mine large quantities of lithium for the energy transition, the Club should develop the capacity to ensure that such critical-mineral mining is done responsibly. The Toiyabe Chapter favors the principles put forth by the Initiative for Responsible Mining Assurance (IRMA) and their certification method to achieve those principles, which is much like LEED certification8. The Club’s Mining Policy referenced above in fact embraces IRMA with:

“Where mining is necessary it must be compliant with high-bar environmental and human rights standards such as the Initiative for Responsible Mining Assurance (IRMA) Standard for Responsible Mining…”

The energy transition cannot be achieved at no cost to the environment and other related factors, but we must work to minimize that cost.

David von Seggern, Ph. D., is a retired seismologist from the Nevada Seismological Laboratory at the U. of Nevada, Reno. He previously worked in the oil and gas explo­ration field and before that on detection and characterization of underground nuclear explosions. Dr. von Seggern is a former chair of the Toiyabe Chapter and closely follows conservation and environment issues in Nevada. References cited in this article may be found in the Notes section on the Desert Report website at