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Mountain Pass history

For over 75 years, Mountain Pass has been a cornerstone of global rare earth production. Once renowned as the world's richest and most reliable source, the site faced years of underinvestment and operational challenges around the turn of the century. In 2015, production was idled. Then, in 2017, MP Materials was founded to revive Mountain Pass—bringing it back to life with renewed strength. Today, the site is more productive than ever, setting new records and serving as the foundation for a full rare earth supply chain in the United States.
 
The Mountain Pass Mine & Processing Facility is situated at an elevation of approximately 4,730 feet (1,443 meters) in San Bernardino County, California.
1865-1895

The early days

1865
The Clark Mining District is organized, named after Senator William A. Clark, the "Copper King" of Montana.
Portrait of William A. Clark
Map of the mining district in Montana
1870-1895
Prospecting and mining of gold, silver, copper, zinc, lead, and antimony take place in the Clark Mining District.
Archival photo showing mining at the Clark Mining Districct
The Mountain Pass deposit is a world-class, exceptionally high grade, and long-life resource. Situated within a 1.4 billion-year-old Precambrian carbonatite intrusion, this unique geological formation contains some of the highest concentrations of rare earth elements globally, primarily in the mineral bastnaesite.

Mountain Pass Facts

Mountain Pass features an expansive open-pit mine measuring approximately 2,500 feet (762 meters) east-west and 3,000 feet (914 meters) north-south and reaching a maximum depth of approximately 600 feet (183 meters).
The site contains one of the world’s highest-grade deposits, averaging approximately 6.0% total rare earth oxides (TREO) over life-of-mine.
With approximately 1.9 million metric tons of rare earth oxides at a 2.4% cutoff, Mountain Pass supports decades of American production.
Located in California's Mojave Desert, Mountain Pass integrates mining, beneficiation, separation, and tailings management into one streamlined, efficient operation.
1977
Unocal acquires Mountain Pass.
Log view of mountains with mining facility
1995-2015

A time of challenges and change

Mountain Pass faces significant challenges and underinvestment. As globalization reshapes the economy, attention on the rare earth industry wanes, allowing production to shift overseas. While its strategic importance is acknowledged, efforts to revitalize Mountain Pass struggle.

2002

Unocal suspends mining.

2005

Chevron acquires Unocal.

2008

Mountain Pass is acquired by an investor group.

2010

Project Phoenix, a $1.7 billion modernization project, is initiated.

2015

Mountain Pass is idled.
MP Materials
In 2017, MP Materials is founded to revive Mountain Pass, rescuing it from the brink of permanent closure.
2017 - present

The MP era

MP’s co-founders, together with an original team of eight, restart mining operations at Mountain Pass and embark on a mission to restore the full rare earth supply chain in the United States.

2017

Setting the foundation

MP restarts mining operations at Mountain Pass.

Mining operations at Mountain Pass
Chart showing employee growth

2018

Achieving first sales
MP begins selling rare earth concentrate.

Products ready for shipping

2019

Scaling up
MP stabilizes production at a run-rate exceeding 30,000 MT of contained TREO, or ~15% of global production.

Overhead shot of mining production
Image of workers

2020

Going public
MP is listed on the NYSE.

Executives giving thumbs up at New York Stock Exchange
Image of mining equiment in use

2021

Establishing a benchmark
MP achieves record annual production of ~42,400 MT of contained TREO.

Overhead image of mining facilities in the daytime

2022

Expanding downstream
MP breaks ground on Independence, a fully integrated metal and magnet manufacturing facility in Texas.

Drone shot of Independence manufacturing facility
People at Bringing the Rare Earth Supply Chain Home booth

2023

Restoring vital capabilities
MP initiates midstream separations and refining operations at Mountain Pass.

MP Materials headquarters building
Bag containing PrNd Oxide

2024

Fulfilling the mission
MP achieves record upstream and midstream production at Mountain Pass. Production of metal and magnets begins at Independence.

The MP Materials Mountain Pass facility
NdFeB Magnets

It is only the beginning

What we have achieved at Mountain Pass and Independence is just the beginning of our journey. We are building a sustainable, resilient supply chain that extends beyond mining and refining to advanced manufacturing. With each milestone, we are driving progress and strengthening American leadership in rare earth production.

Setting Records

MP has consistently scaled production to new highs, raising the bar for performance in the 75-year history of Mountain Pass.

Expanding Capabilities

We continue to strengthen our position in the global supply chain and are working to meet rising demand.

Always Advancing

MP is committed to continuously raising the bar for environmental health and safety.

Learn more

Uncover the spirit that drives our mission.
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