The definitive answer is that lithium is not a rare earth metal. This confusion often arises from its importance in modern technology, particularly in batteries, and its role as an indispensable component in the transition to renewable energy. While lithium is considered a “critical” material, its chemical classification and properties place it in a completely different category from the rare earth group. The distinction is one of fundamental chemistry, geological occurrence, and economic terminology.
Defining Rare Earth Elements
Rare Earth Elements (REEs) are a strictly defined set of 17 metallic elements on the periodic table. This group is composed of the 15 lanthanide elements, plus Scandium and Yttrium. Scandium and Yttrium are included because they typically occur in the same mineral deposits as the lanthanides and exhibit similar chemical behaviors.
These elements are characterized by their similar chemical properties, largely due to the unique electronic configuration involving their f-orbitals. This structure gives them distinct magnetic, luminescent, and catalytic properties used in high-tech applications, such as permanent magnets in electric vehicles and wind turbines. The term “rare earth” is misleading; these elements are relatively plentiful in the Earth’s crust, with the most abundant, Cerium, being more common than copper. However, they are geochemically dispersed and rarely found concentrated enough to be economically extracted, which historically led to the name.
Lithium’s Actual Classification and Characteristics
Lithium is correctly classified as an Alkali Metal, belonging to Group 1 of the periodic table. This classification is entirely separate from the Rare Earth Elements, which are clustered in the inner transition metals and Group 3. Lithium is the lightest of all solid elements.
As an alkali metal, lithium is soft, highly reactive, and readily loses its single valence electron to form a positive ion. This high reactivity and unique lightness are the properties that make it ideal for use in high-energy-density lithium-ion batteries. Geologically, lithium is found in two primary forms: hard-rock minerals like spodumene, and brines, which are salt-rich waters often located beneath dry lake beds.
Distinguishing Geological Rarity from Economic Criticality
The confusion between lithium and rare earth metals stems from conflating two distinct concepts: geological rarity and economic criticality. Rare Earth Elements are chemically unique, defined by their dispersed nature, which makes separation technically difficult and costly. Their supply chain involves complex separation and refining processes, which defines their scientific “rarity.”
Lithium, conversely, is not chemically rare but is classified as a “critical mineral.” An element becomes critical when its supply chain is vulnerable to disruption and its absence would have significant negative consequences for major industries, such as the electric vehicle and renewable energy sectors. Lithium’s value is driven by unprecedented demand for energy storage, which is projected to rise dramatically over the coming decades.
This demand, coupled with specific challenges in extraction—whether from the slow, water-intensive process of brine evaporation or the energy-intensive processing of hard rock—creates supply risk. While lithium shares supply chain vulnerabilities and strategic importance with rare earth metals, the reason is economic and geopolitical, not a shared scientific classification. The term “critical” reflects its function in modern technology, not its geological scarcity.