75 D1. Recent Advances in Economic Geology

Monday, 23 September 2024
8:00 AM - 12:00 PM
204A

MOUNTAIN PASS, CALIFORNIA & PERSPECTIVE ON REE ECONOMICS

Paper number: 75-12
Program: Technical Sessions
Time: 10:20 AM – 10:35 AM

Authors

Abstract

The history of mining at Mountain Pass (Mt Pass) started in 1924 when prospectors found galena on Sulphide Queen Hill, a mile north of Mt Pass and claims were filed with no ore ever shipped. From 1939 to 1941 gold was discovered and mined from the gold and galena bearing quartz veins. Molycorp bought the claims in 1950 for the REE-bearing carbonatite. Currently the average ore grade is approximately 8% with a cut off 2.3% rare earth elements (REE). The Mt Pass carbonatite is associated with a suite of 1.4 GA ultrapotassic rocks with abundant F, Th, K, Ba, Rb, Cs + REE (bastnasite).

Molycorp had a worldwide exploration program for carbonatites that included the discovery of the only producing REE mine in Australia, and economic evaluation of hundreds of other prospects which have been in the news as potential new mines. As late as the mid-1980’s, Mt Pass led the world in rare earth production and innovation. This leadership was wrested from Molycorp by Chinese national interests using their own rare earth carbonatite orebody (Bayan Obo) and by acquiring western technology. While China produces about 68% of the world’s REE they process 90% of REE including the ore from Mt Pass. Mountain Pass is owned by MP Materials (NYSE:MP) and is one of the only locations extracting rare earth elements (REE) in the U.S. The economics of rare earth production by MP Materials is still affected by Chinese interests and competition. Production of separated rare earths is now beginning.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-401799

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