Wednesday, August 11, 2021, 11:00am-12:00pm (Pacific Time)
(NOTE: At the request of the speaker, this presentation was not recorded.)
TITLE: Lithium: Geochemistry and Economic Geology
The global pursuit of independent power and low-carbon, renewable energy is driving efforts to quantify worldwide lithium (Li) resources and reserves, and to explore for new deposits.
Although the current interest in Li is for its use in batteries, Li is used in many industries: ceramics and glass, electronics, organic and polymer chemistry, medicine, aluminum production, and also in the production of greases and lubricants, and desiccants for air filtering devices. It is the chemical properties of lithium that make it useful: its density is 0.543 g cm-3, making it the lightest of all solids in the periodic table; it has the highest heat capacity of all solids, 5.38 kJ kg-1 K-1; and its melting and boiling temperatures, 180.5 and 1342oC, respectively, are the highest of the alkali metals.
Lithium was first discovered in 1817 when it was isolated from the mineral petalite, but it was not produced in large quantities until 1855. In 1898 it was mined as the mineral spodumene from the Etta pegmatite in South Dakota. Other pegmatite mines in CA, NM, and SD began Li production soon after and in the early 1900s the US dominated the global supply. The earliest production of Li from brine began in 1938 from Searles Lake, CA, and a larger brine deposit was developed at Clayton Valley, NV, in 1966. Today, brine resources in South America and pegmatite resources in Australia are among the largest sources of Li to the global economy.
To put the Li commodity cycle into perspective, current global Li reserves are 21,000,000 metric tons Li, while US reserves are at 750,000 metric tons Li. The only U.S. production is from the brine deposit in Clayton Valley, NV, which produced approximately 6000 metric tons of Li in 2018. In 2019, global and US consumption was estimated at approximately 56,000 and 2,000 metric tons Li, respectively.
According to the USMIN database, maintained by the U.S. Geological Survey (USGS), the largest Li deposits in the US are in Nevada. These are Li-clay deposits found in the McDermitt Caldera, Rhyolite Ridge, and playa surfaces in Clayton Valley and the Bonnie Claire Basin. Cooperative research between the USGS and University of Nevada, Reno has revealed Li contents in the clays alone can range from 1000 to 12,000 ppm Li. Current studies are focused on understanding the depositional environment and alteration history of these clays.
Dr. Lisa Stillings is a Research Geologist with the U.S. Geological Survey (USGS) and an Adjunct Professor in the Department of Geological Sciences and Engineering at the University of Nevada Reno (UNR). Her research with UNR faculty and students has included microbially-mediated redox reactions, chemistry of mining-related pit lakes, transport and retention of tungsten and selenium in the environment, and the geochemistry and mineralogy of lithium in aquifers and sediments. Prior to starting with the USGS she worked for environmental consultants in PA, MI, OH, and CO. Her PhD research at Penn State University was on the kinetics of feldspar dissolution and weathering.