EXPLORATION AND DEVELOPMENT AT THE THACKER PASS LITHIUM CLAYSTONE DEPOSIT, NORTHERN NV: UNLOCKING A DOMESTIC ENERGY REVOLUTION

The Thacker Pass Project in northern Nevada is the first lithium clay project to break ground in the world and is the first lithium project permitted in the United States in half a century. The lithium-rich clays are hosted in lacustrine sediments located in the southernmost portion of the ~16.3 Ma McDermitt caldera, the largest known lithium deposit in the world (Benson et al., 2023). This project, now under construction, is therefore critical for the development of a domestic supply chain of lithium. Lithium exploration was originally undertaken at the Thacker Pass site by Chevron in the late 1970’s when, during a prospecting campaign for Uranium, they were alerted to the presence of lithium by the USGS. Chevron subsequently launched a drilling and metallurgical testing campaign to understand the economic potential for this lithium resource. In 2007, Western Lithium USA Corp. took over the project with the intent of developing the lithium asset, and eventually changed the company’s name to Lithium Americas in 2016 and changed the project from the Kings Valley Lithium Property to the Thacker Pass project in 2018. Since taking over the project, Lithium Americas carried out several important steps beyond just understanding the geology, including completion of all environmental assessments, securing the correct state and federal permits, signing a first-of-its-kind Community Benefits Agreement with the nearest tribe, and research and development of a novel process to extract the lithium from the clay. Critical to the development of the resource and the new extraction process, Lithium Nevada engaged in rigorous outreach with the global scientific community. The academic collaborations that the Lithium Nevada team was able to build were incredibly valuable for understanding the geologic history of the deposit, including how the lithium entered into the magma and ultimately how it was incorporated into the structure of the illite and smectite clays in the lacustrine system at the McDermitt Caldera. Additionally, these collaborations have improved the mineralogy of the project to help the engineering team design an optimized and economic flowsheet for extracting the lithium from the clays. The long history of engagement with a wide variety of stakeholders – from open houses and student field trips for local residents to collaborations with the vast scientific community – is an excellent example of the process required to bring critical mineral projects online domestically in the 21^st century.