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Mountain Pass Carbonatite and Rare-Earth Deposit

Project Chief:

Ed Dewitt
[For inquiries about this project, please contact Doug Stoeser.]

Project Objectives

Rare earth elements are critical to many modern technologies and the United States is presently dependant on imports. The Mountain Pass carbonatite deposit in southeastern California contains the world's second largest and highest grade light rare earth element (REE) deposit. The deposit is a premier source of light rare earth elements outside of China. Given the long time required to bring new deposits into production, Mountain Pass may be the dominant producing U.S. rare earth element deposit for the foreseeable future. Since the discovery of the Mountain Pass carbonatite deposit in 1949, the USGS has been instrumental in research on the deposit and the Mountain Pass district (Olson and others, 1954; DeWitt, 1987; DeWitt and others, 1987, 2000; Rowan & Mars, 2003; Haxel, 2005, Mars & Rowan, 2010; DeWitt and others, in prep.). The only other major paper on Mountain Pass is that of Castor (2008). Despite the previous work, the deposit's origin and evolution remain enigmatic. The lack of clear understanding about the deposit's genesis hinders the development of a robust deposit model for carbonatite-hosted rare earth element deposits, and the associated parameters that might be used as exploration guides for undiscovered deposits.

The project objectives are to better understand the genesis and evolution of the Mountain Pass rare-earth carbonatite deposit and its associated silicate intrusive rocks. Study goals are: (a) to build upon the present base of petrologic, mineralogic, geochronologic, isotopic and geochemical information to understand the genesis of the deposit, and (b) provide base information to advance deposit models and exploration guidelines for rare earth element-carbonatite deposits. Knowledge of the deposit can be used for assessment and exploration for similar deposits.

References Cited

Mineral Resources Program
Eastern Central Western Alaska Minerals Information Crustal Geophysics and Geochemistry Spatial Data

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