Mountain Pass, California is a small–unincorporated community located in San Bernardino County, California fifteen miles southwest of Primm. With an elevation of over 4,700 feet, Mountain Pass is the highest point on Interstate 15 in California. Despite being in the Mojave Desert, its elevation causes it to receive more precipitation than the low lying areas and it supports more plant life. Creosote scrub and Joshua trees grow in the area.
Mountain Pass has a cooler climate than the surrounding desert valleys. Average high temperatures in the summer are near 90 degrees with low temperatures in the 60s. Daytime highs in the winter are typically in the 50s with lows slightly below freezing. Mountain Pass averages eight inches of precipitation per year, three inches more than Primm. In the winter, the area receives occasional snowfall, with a modest average amount of nine inches per year.
There is a rare-earth minerals mine in Mountain Pass that has an interesting history. It has deposits of bastnäsite, from which the following can be extracted: Cerium, Neodymium, Europium, and Lanthanum. Europium is used for the red light in cathode ray tube ("CRT") screens. The Mountain Pass mine made the U.S. the world's largest producer of rare-earth minerals.
The mine has been shut down in the past and has a history of opening and closing due to environmental concerns. In the 1980s and 1990s, the owner of the mine was pumping wasterwater to evaporation ponds near Ivanpah Dry Lake. This pipeline repeatedly ruptured, leaking radioactive matter into the desert flooor due to the presence of thorium and radium. Due to the federal authoring findings, the copany had to pay more than $1.4 million in fines and settlements. The company also had to prepare a cleanup plan and copmlete an extensive environmental study.
Due to the increasing demand for these rare earth metals, the mine resumed full operations in 2013. However, in 2015 the company that owns the mine declared bankruptcy and the mine closed again.
In 2017, the mine was sold for $20.5 million to MP Mine Operation, a company based in China, and has resumed operation. Rare-earth elements are a critical component of an emerging, large industry, electrical vehicles, which helped spur the re-birth. Outside of Mountain Pass, China and Japan are the only current sources for rare-earth magnetic material.
Mountain Pass sits at the southern edge of the Clark Mountain Range. The range extends for about fifteen miles in a southwest–northeasterly direction. Its tallest peak, Clark Mountain, at 7,933 feet, is five miles northwest of Mountain Pass. Pinyon pines, juniper, and rare white fir trees grow at the higher elevations.
Clark Mountain is also a world–class rock climbing area. Its exposed limestone rock attracts climbers from all over.