Today, let’s take a look at interesting facts about Lanthanum and answer the following questions: “Why Is Lanthanum Considered A Rare Earth Element?”, and “Why Is Lanthanum Considered A Critical Raw Material?”

Check out the rest of the light rare earth elements here – ‘20 Interesting Facts About The Light Rare Earth Elements (LREEs)’

Why Is Lanthanum Considered A Rare Earth Element?

Lanthanum is considered a rare earth element because it is the first member of the lanthanide series, the group of 15 elements that form the core of the rare earth elements. With atomic number 57, lanthanum begins the lanthanide series that extends through lutetium (atomic number 71). The lanthanides are defined as “the 15 elements that range in atomic number from 57 (lanthanum) to 71 (lutetium)” and are “commonly referred to as the ‘lanthanides.'” As the namesake element of the lanthanide series (literally meaning “hidden” in Greek, reflecting its initial discovery hidden within cerium minerals), lanthanum establishes the chemical and physical properties that characterize the entire rare earth element group.

Lanthanum exhibits all the defining chemical characteristics of rare earth elements. It possesses the typical trivalent oxidation state (La3+) common to all REEs and has the largest ionic radius among the lanthanides, beginning the systematic “lanthanide contraction” – the progressive decrease in ionic radius from lanthanum to lutetium. With a crustal abundance of 39 parts per million, lanthanum is more abundant than copper or lead, yet like other rare earth elements, it rarely concentrates into economically viable deposits. This geochemical behavior means lanthanum invariably occurs with other rare earth elements in nature, particularly in the primary REE minerals bastnäsite ((REE)CO3F), monazite ((REE,Th)PO4), and xenotime, where “REEs can substitute for one another in crystal structures.”

From both historical and practical perspectives, lanthanum epitomizes the rare earth element group. Discovered in 1839 by Carl Gustaf Mosander, lanthanum was one of the first rare earth elements identified, originally found as an impurity in cerium minerals – highlighting the characteristic co-occurrence of rare earth elements. Industrially, lanthanum’s applications reinforce its rare earth status: it is used alongside other REEs in mischmetal (containing “65% cerium, 35% lanthanum”), in lanthanum-nickel-hydride batteries that can contain “10 to 15 kilograms per electric vehicle,” and as lanthanum-based catalysts in petroleum refining. These applications leverage lanthanum’s chemical properties that are intrinsically linked to its position as a rare earth element. 

The combination of lanthanum’s foundational position in the lanthanide series, its defining chemical properties including the La3+ oxidation state, its invariable co-occurrence with other REEs in nature at predictable ratios, and its industrial applications alongside other rare earth elements firmly establishes lanthanum as not just a rare earth element, but as the archetypal member that defines the entire group.

Why Is Lanthanum Considered A Critical Raw Material?

Lanthanum is considered a critical raw material due to its indispensable role in clean energy technologies, petroleum refining, and advanced optical applications, combined with severe supply chain vulnerabilities. Lanthanum is essential for nickel-metal hydride batteries, which “contain significant amounts of lanthanum, requiring as much as 10 to 15 kilograms per electric vehicle.” These batteries remain important in hybrid vehicles despite competition from lithium-ion technology. Additionally, lanthanum-based catalysts are crucial for petroleum refining, where they enable the cracking of heavy hydrocarbon molecules into lighter, more valuable products. This application alone represents a massive industrial demand, as catalysts constitute one of the largest end uses for rare earth elements globally. In optical applications, “lanthanum makes up as much as 50 percent of digital camera lenses, including cell phone cameras,” demonstrating its penetration into ubiquitous consumer technologies.

The criticality of lanthanum is amplified by extreme supply concentration and geopolitical risks. Between 2011 and 2017, China produced approximately 84% of the world’s rare earth elements, with the United States contributing only about 4% during its limited production from 2012-2015. This concentration is particularly significant for lanthanum because it represents one of the largest components of rare earth deposits – comprising 34.00% of REO content at Mountain Pass, California, and 23.00% at Bayan Obo, China. When China announced export restrictions in 2010 through quotas, licenses, and taxes, it highlighted the vulnerability of lanthanum-dependent industries. The fiscal year 2024 National Defense Stockpile plan includes 1,300 metric tons of lanthanum for potential acquisition, representing one of the largest quantities of any individual rare earth element targeted for strategic reserves.

The strategic importance of lanthanum extends across multiple critical sectors of the modern economy. In petroleum refining, lanthanum-based fluid catalytic cracking (FCC) catalysts are essential for producing gasoline and other light hydrocarbons from crude oil. The glass industry, identified as “the largest consumer of REE raw materials,” depends heavily on lanthanum for specialized optical properties and high refractive index applications. Lanthanum is also a key component of mischmetal (containing “65% cerium, 35% lanthanum”) used in steelmaking to remove impurities and produce special alloys. The broad industrial application of lanthanum means that supply disruptions would impact everything from fuel production to consumer electronics manufacturing.

The processing complexity and limited refining capacity outside China further compound lanthanum’s criticality. While lanthanum is relatively abundant in rare earth deposits, separating it from other REEs requires sophisticated solvent extraction facilities, most of which are located in China. Price data reflects this supply vulnerability – lanthanum oxide has maintained relatively stable pricing at around $2/kg only because it is produced in large quantities as a byproduct of processing for higher-value rare earths. However, any disruption to rare earth mining or processing would immediately impact lanthanum availability. Expert panels from the National Research Council, U.S. Department of Energy, and European Commission have consistently ranked rare earth elements including lanthanum as having high “criticality” ratings. 

The combination of lanthanum’s essential roles in petroleum refining, clean energy storage, optical technologies, and metallurgy, coupled with its concentrated supply chain and lack of adequate substitutes, firmly establishes lanthanum as a critical raw material for industrialized economies. The element’s importance is underscored by its inclusion in strategic stockpile planning at quantities exceeding most other rare earth elements, reflecting both its high consumption rates and strategic significance.

Interesting Facts About Lanthanum

1. Lanthanum is the first element in the lanthanide series and gives its name to the entire group, despite not technically being an f-block element itself (its electron configuration ends in 5d¹ rather than 4f).
2. It has an unusually low melting point (920°C) for a metal with such a high atomic number, making it one of the softest rare earth elements.
3. Lanthanum exhibits a unique phase transition at 310°C where it transforms from a double hexagonal close-packed structure to a face-centered cubic structure, then to body-centered cubic at 868°C.
4. Pure lanthanum is pyrophoric – it spontaneously ignites in air at temperatures above 150°C, requiring storage under mineral oil or inert gas.
5. Lanthanum has the second-highest superconducting transition temperature (6.00 K at atmospheric pressure) among all elemental superconductors, surpassed only by niobium.
6. It forms the basis for mischmetal, an alloy containing 25-45% lanthanum that creates the sparks in cigarette lighter flints when alloyed with iron.
7. Lanthanum oxide (La₂O₃) has one of the highest refractive indices of any compound (n = 2.1), making it crucial for high-quality camera and telescope lenses.
8. Unlike most rare earth elements, lanthanum readily forms a stable +2 oxidation state in addition to the typical +3, particularly in organometallic compounds.
9. Lanthanum carbonate is used as a phosphate binder medication for patients with kidney disease, as it binds dietary phosphate in the gut without being absorbed.
10. It has an exceptionally large atomic radius (187 pm) and ionic radius (103.2 pm for La³⁺), the largest of all the lanthanides.
11. Lanthanum-barium-copper oxide was one of the first discovered high-temperature superconductors, with a critical temperature of 35 K.
12. The element exhibits paramagnetic properties at room temperature but becomes antiferromagnetic below 54 K, an unusual magnetic transition.
13. Lanthanum nickel hydride (LaNi₅H₆) can reversibly store hydrogen at room temperature, making it valuable for hydrogen storage applications.
14. It has 39 known isotopes, but only two occur naturally: stable La-139 (99.91%) and radioactive La-138 (0.09%) with a half-life of 102 billion years.
15. Lanthanum forms unique “superhydrides” under extreme pressure (LaH₁₀) that exhibit superconductivity at temperatures as high as 250 K (-23°C).
16. The element’s name comes from the Greek “lanthanein” meaning “to lie hidden,” as it was concealed in cerium minerals for 36 years before isolation.
17. Lanthanum-modified lead zirconate titanate (PLZT) becomes transparent when electrically polarized, enabling optical shutters and displays.
18. It has the highest heat of vaporization (400 kJ/mol) among the light rare earth elements, indicating unusually strong metallic bonding.
19. Lanthanum catalysts are uniquely effective at breaking carbon-carbon bonds in petroleum refining, particularly in fluid catalytic cracking processes.
20. The element forms distinctive blue solutions when dissolved in liquid ammonia, producing solvated electrons that make these solutions powerful reducing agents.

Thanks for reading!