Lithium is found throughout nature, but never as a pure metal. It exists in trace amounts in most rocks, soils, natural waters, and even the ocean. Because lithium is an alkali metal and extremely reactive, it always bonds with other elements, forming minerals, dissolved salts, and clay deposits. The Earth’s crust contains about 30 parts per million of lithium, making it moderately abundant but widely dispersed.
Why Lithium Never Exists as a Free Metal
Lithium belongs to the alkali metal group, the most reactive family on the periodic table. It readily gives up an electron to bond with other elements, always carrying a +1 charge in nature. Drop pure lithium into water and it reacts immediately, producing hydrogen gas and heat. This reactivity means every bit of lithium on Earth is locked inside minerals, dissolved in water, or bound within clay structures. Extracting usable lithium always requires breaking these chemical bonds.
Hard Rock Deposits in Pegmatites
The richest concentrations of lithium in solid rock occur in pegmatites, coarse-grained igneous formations that crystallize from the last stages of cooling magma. Four minerals account for most of the lithium found in these rocks: spodumene, lepidolite, petalite, and amblygonite.
Spodumene is the most commercially important. It has a nearly perfect lithium aluminum silicate composition and contains roughly 8% lithium oxide by weight, the highest concentration among common lithium minerals. Major spodumene pegmatite deposits are mined across Western Australia at sites like Greenbushes, Kathleen Valley, and Mount Marion. Australia produced an estimated 88,000 metric tons of lithium in 2024 and holds reserves of 57 million metric tons, the largest of any country.
Lepidolite, a lithium-rich mica, and petalite, a lithium aluminum silicate, are less commonly mined but still significant. Their lithium content varies and tends to be lower than spodumene’s. Pegmatite deposits collectively account for about 26% of the world’s identified lithium resources.
Brine Deposits in Closed Basins
The single largest source of lithium resources isn’t rock at all. It’s brine: lithium-rich saltwater trapped beneath the dry lake beds (salars) of arid, high-altitude basins. These deposits hold an estimated 58% of global lithium resources.
Over thousands of years, rainwater and snowmelt dissolve lithium from surrounding volcanic rocks and carry it into basins with no outlet. The water evaporates under intense sun, concentrating lithium along with sodium, potassium, and magnesium in underground pools. The Salar de Atacama in Chile and the salars of northwestern Argentina are the most productive. Chile holds reserves of 9.3 million metric tons and produced roughly 49,000 metric tons in 2024. Argentina, with reserves of 4 million metric tons, produced about 18,000 metric tons the same year.
Extracting lithium from brine typically involves pumping the saltwater to the surface and letting it evaporate in large ponds, a process that takes months and consumes vast stretches of land. The lithium gradually concentrates as water disappears, leaving behind salts that can be chemically processed.
Lithium Clays and Volcanic Sediments
A less well-known source is lithium-bearing clay, which forms when volcanic ash in ancient lake beds gets altered by hot, mineral-rich fluids rising along fault lines. The main lithium clay mineral is hectorite, a member of the smectite family. It contains only about 0.5% lithium by weight, far less than spodumene, but can occur in thick, extensive deposits near the surface that are relatively easy to access.
The most significant lithium clay deposit discovered so far sits within the McDermitt caldera complex, an extinct volcanic center straddling the Nevada-Oregon border. The mineral gets its name from an earlier discovery at Hector, California, where lake beds of volcanic ash were transformed by hydrothermal fluids. Lithium clay deposits share a common recipe: lake sediments, volcanic material, and evidence of hydrothermal alteration. Together, they represent about 7% of global lithium resources.
One unusual deposit breaks the mold entirely. In Serbia’s Jadar Valley, thick layers of jadarite (a boron-lithium silicate related to zeolites) formed in an ancient basin system. Jadarite contains about 3.4% lithium by weight, and this single deposit holds an estimated 3% of the world’s lithium. It is the only documented lithium-zeolite deposit of its kind.
Lithium in the Ocean
The world’s oceans contain roughly 180 billion tons of dissolved lithium, dwarfing all land-based reserves combined. But the concentration is tiny: about 0.2 parts per million. Sodium, a chemically similar element, is roughly 100,000 times more abundant in seawater, and any extraction system tends to pull in sodium along with the lithium, crowding it out.
Researchers have experimented with specialized electrodes and membranes to selectively capture lithium from seawater, but no approach has proven cheap enough to compete with mining on land. The sheer volume of water that must be processed, combined with the difficulty of separating lithium from sodium, keeps oceanic lithium a future possibility rather than a current source.
Lithium in Drinking Water and Soil
Lithium occurs naturally in groundwater at levels that vary dramatically by region. A USGS study using data from 18,000 wells found that groundwater across much of the western and southwestern United States (Montana, Wyoming, the Dakotas, Colorado, Utah, Nevada, Arizona, New Mexico, and Texas) contains lithium at concentrations of 30 micrograms per liter or higher. Eastern and northeastern states generally have lower concentrations, though pockets above 30 micrograms per liter exist there too.
These trace amounts enter groundwater as it slowly dissolves lithium from surrounding rocks and sediments. Soils pick up lithium the same way, and plants absorb small quantities through their roots. Grains, vegetables, and drinking water all contain measurable traces, though the amounts depend heavily on local geology. Areas with lithium-rich volcanic or granitic bedrock tend to have higher levels in both water and food.
Where the Biggest Reserves Are
Lithium resources are unevenly distributed around the globe. Australia leads in total reserves at 57 million metric tons, largely from its extensive pegmatite deposits. Chile follows with 9.3 million metric tons, concentrated in brine beneath the Atacama Desert. Argentina holds 4 million metric tons, also primarily in brine form.
The type of deposit shapes how lithium is extracted. Hard rock mining dominates in Australia, where spodumene ore is crushed and chemically processed. Brine evaporation dominates in South America. Clay deposits in the western United States are still largely in development. Each source has a different lithium concentration, extraction cost, and environmental footprint, which is why the geography of lithium deposits directly influences global supply chains and pricing.