Bastnasite-Ce

specimen number:
2354154

location:
Mountain Pass Mine, San Bernardino Co., California, USA

description:
An extremely rich example for the species and locality, solid pink masses of bastnasite-Ce with minor goethite.

Located in the Clark Mountain Range of San Bernardino County, California, the Mountain Pass Mine is a world-famous open-pit rare earth element deposit centered on a Mesoproterozoic carbonatite intrusion cutting through ancient granitic gneiss. Discovered in 1949 by uranium prospectors using Geiger counters, the site was rapidly developed by the Molybdenum Corporation of America (Molycorp) and became the primary global producer of rare earths from the 1960s through the 1990s. The ore body is exceptionally rich in cerium-group lanthanides, dominated by massive yellow to reddish-brown honey-colored bastnasite, a fluorcarbonate mineral that forms the principal commercial source of light rare earths at the site. Operations slowed significantly in the early 2000s due to environmental and competition issues, but modern processing facilities have since revitalized commercial mining. Collecting at the site is strictly prohibited due to active commercial operations and industrial site hazards, though classic historic specimens remain prized additions to rare-earth mineral collections.

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