CRITICAL MINERAL ASSESSMENT OF GRAPHITE—QUANTIFYING GLOBAL GRADE AND TONNAGE DATA AND IMPLICATIONS FOR UNITED STATES DOMESTIC SUPPLY

Crystalline graphite is a primary material in lithium-ion battery anodes used in electric vehicles. Forecasts for 2040 anticipate an order of magnitude increase in graphite demand driven by sustainable development policies to reduce carbon emissions. Domestic production of graphite peaked during World War I, steadily declined, and eventually ceased in the 1980s. The United States (U.S.) relies on natural graphite imports from producers such as China or high-cost synthetic graphite. To inform decision makers on domestic supply potential, the U.S. Geological Survey is conducting a critical mineral resource assessment for graphite that includes a modern mineral inventory compilation and updated grade and tonnage model for disseminated flake graphite deposits.

This contribution to the national graphite assessment aims to 1) compile graphite mineral site data from multiple sources, 2) improve the spatial accuracy and attributed information of each record, and 3) compare the grade, tonnage, and spatial extent of global and domestic deposits. Compiling information contained in historic publications and modern technical reports requires documenting, adjudicating, and reconciling records with variable attribution and spatial accuracy. Utilizing historical information stored in legacy databases combined with state-of-the-art tools and high-resolution LiDAR elevation data enables the construction of an enhanced mineral site compilation with accurate locations and standardized attributes.

Relative to the model published in 1992, the 100 well-explored global deposits included in the updated grade and tonnage model host significantly larger resources than previously reported. The updated grade and tonnage model implies economically relevant deposits likely contain a median of 0.9 million metric tons (Mt) of contained graphite. Ore tonnages range from 0.8 Mt in the 10^th quantile (Q10) to 100 Mt in the 90^th quantile (Q90) with a median of 10 Mt. Grades range from 3 weight percent (wt. %) graphitic carbon (C­_g) in Q10 to 20 wt. % C­_g in Q90, with a median of 9 wt. % C­_g. The updated grade and tonnage model provides essential information for evaluating domestic graphite resources and highlights the economic potential for graphite from the Appalachian crystalline rocks in New York, Pennsylvania, and Alabama.