Lithium Brine Pools: Salars, Ponds and Brine Grades

Lithium brine is salty groundwater, found beneath dry salt flats and in some deep sedimentary basins, that carries dissolved lithium chloride. The best-known example is the Salar de Atacama in Chile, where the USGS gives an average of about 1,400 parts per million (ppm) lithium, roughly 1,400 milligrams per kilogram of brine (USGS Professional Paper 1802-K, 2017). The “lithium brine pools” people search for are the shallow, lined evaporation ponds where that brine is left in the sun until the lithium is concentrated. They are not natural lakes of lithium, and they are not the deep-sea brine pools found on the ocean floor.

This page answers the questions a consultant, licence holder or investor usually has first: what grade counts as good brine, how pond evaporation compares with direct lithium extraction (DLE), where the deposits are, and what the numbers look like in the ground. For the plant-side steps after the ponds, see our guide to the lithium brine extraction process; this page stays with the resource and the pond stage.

How good is lithium brine? Grades in ppm and mg/L for the main salars

Brine grade is quoted as milligrams of lithium per litre (mg/L), or as ppm. The two are close but not identical: brine is denser than fresh water, so a figure in mg/L is a little higher than the same brine in ppm by mass. Always check which unit a company or paper uses before comparing two deposits.

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Average lithium in four brine deposits

parts per million lithium, USGS averages

The USGS lists these averages for well-studied closed basins: about 1,400 ppm at the Salar de Atacama in Chile, about 700 ppm at Zabuye Lake in Tibet, about 320 ppm at the Salar de Uyuni in Bolivia and about 160 ppm at Clayton Valley in Nevada (USGS, 2017). Grade is only one lever. A big, thick, permeable salar with a lower grade can hold more lithium than a small, rich one. The Salar de Uyuni is the example: the USGS estimates about 9 million tonnes of lithium there at an average near 320 ppm, against about 7.5 million tonnes at Atacama at 1,400 ppm.

Oilfield brines are a second type. The USGS reports lithium up to 700 ppm in deep oilfield brines in several US states, and up to 692 mg/L in places in the Smackover Formation, which lies at depths of 1,800 to 4,800 metres (USGS, 2017). Because those brines sit deep, outside a sunny closed basin, solar ponds are not the obvious route, and they are usually discussed alongside DLE.

How evaporation ponds on lithium salt flats work

On a salar, wells pump brine from beneath the salt crust into a chain of shallow ponds. The sun and wind remove water, the brine gets saltier, and different salts drop out of solution in a set order. Separate ponds keep those salts apart, so the lithium stays in the liquid while sodium chloride, potassium and magnesium salts crystallise out first.

The USGS describes the Clayton Valley operation as brine averaging about 160 ppm lithium pumped through nine ponds covering 16 km². After nearly 2 years the liquid is enriched to about 5,000 ppm lithium, and this “mother liquor” goes to a chemical plant that makes lithium carbonate and lithium hydroxide (USGS, 2017). A peer-reviewed study of two Argentine projects puts the evaporative concentration phase at typically 12 to 18 months (peer-reviewed water footprint study, 2025). NASA notes that at the Salar de Uyuni brine usually stays in the pools for about six months, and that rainy, cool weather there slows evaporation compared with other operations in the region (NASA Earth Observatory).

That is why the same salt flat can look different in two satellite images: pond colour shifts with salt type and concentration, and a wet season can stall the process. Magnesium is the main trouble. NASA reports that Uyuni brine has unusually high magnesium and potassium that must be removed, which raises cost, and the USGS says the magnesium can pull lithium out of solution early as an impurity in magnesium salts.

1. Pump: production wells draw brine from the salar aquifer into the first pond.
2. Concentrate: the brine moves through a series of ponds as water evaporates.
3. Separate: common salts crystallise first and are left behind in the earlier ponds.
4. Finish: the lithium-rich liquor goes to a plant where it is cleaned and turned into lithium carbonate or hydroxide.

Evaporation ponds versus direct lithium extraction

Direct lithium extraction is a group of technologies that pull lithium out of brine with sorbents, membranes or solvents instead of letting the sun evaporate the water. A 2022 review in Nature Reviews Earth & Environment says DLE aims to avoid brine evaporation, and that some DLE technologies have reached lithium recovery above 95%. It also warns that only 30% of DLE test experiments used real brines, and that many DLE processes may need more fresh water than ponds do, which matters in arid places (Nature Reviews Earth & Environment).

A direct comparison from operating plants helps. A study using environmental impact reports for Olaroz (evaporation ponds) and Fénix (DLE), both in Argentina, found brine consumption in 2021 of about 537 m³ per tonne of lithium carbonate at Olaroz and about 320 m³ at Fénix. Its water footprint was 51.0 m³ per tonne at Olaroz and 135.5 m³ at Fénix, so the DLE site used less brine but more fresh water (peer-reviewed study, 2025). Two plants are a small sample, and the study relies on company reports, so treat it as a comparison of two sites rather than a rule.

Recovery is the figure that differs most between projects, so use the one in the project’s own technical report rather than a general average.

Where lithium brine deposits are

Most of the world’s brine lithium sits in closed basins in the high Andes of Chile, Argentina and Bolivia, in Tibet and Qinghai in China, and in the western United States. The USGS estimates measured and indicated lithium resources of about 150 million tonnes worldwide, with Argentina at 28 million, Bolivia 23 million and Chile 13 million (USGS Mineral Commodity Summaries, 2026). Those totals include every deposit type, so Australia, China, Germany and Canada also appear because of hard-rock, clay or geothermal resources. For the Argentine side, see our guide to the lithium triangle.

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Measured and indicated lithium resources by country

million tonnes of lithium, all deposit types, selected countries

Bolivia’s Salar de Uyuni covers more than 10,000 km² and NASA reports only a small share has been mined so far. Rankings differ by source: the USGS (2017) estimates about 9 million tonnes of lithium there, more than the 7.5 million at Atacama, while NASA describes it as the second-largest deposit (NASA Earth Observatory). The Salar de Atacama is the world’s most significant lithium district by USGS’s description, and it is also where ownership has changed lately. In December 2025 Codelco and SQM completed the NovaAndino Litio joint venture to run lithium at the Salar de Atacama until 2060 (Codelco press release, 27 December 2025). In a separate deal, Codelco signed an agreement in May 2025 for Rio Tinto to take 49.99% of a Salar de Maricunga joint venture, with closing expected in the March quarter of 2026 and subject to regulatory steps (International Mining, 19 May 2025).

Production tells a related story. Chile mined an estimated 56,000 tonnes of contained lithium in 2025 (up from 48,900 in 2024), Argentina 23,000 (from 13,800) and China 62,000 (from 41,400), per the USGS. Australia, the largest producer at 92,000 tonnes, mines hard rock rather than brine; see our note on lithium extraction in Australia and the spodumene pegmatites of James Bay for that other deposit type.

Lithium brines in the United States

US commercial lithium production comes from a continental brine operation in Nevada, according to the USGS (USGS, 2026). A USGS remote-sensing study of the Basin and Range Province found 89 playas (dry lake beds) larger than 6 km², and notes Clayton Valley as the only lithium brine-producing playa in the United States at the time of the report (USGS Scientific Investigations Map 3554).

The other large target is deep oilfield brine. A USGS fact sheet estimates that between 5.1 and 19.0 million tonnes of lithium are in place in Smackover Formation brines in southern Arkansas, and says that figure does not consider whether extraction is technically or economically possible (USGS Fact Sheet 2024-3052). Across the Gulf Coast, measured lithium in Smackover and other brines ranged from 0.08 to 1,700 mg/L, though only 3 of 544 samples exceeded 500 mg/L and those high values could not be verified. The machine-learning model predicted 3.7 to 408 mg/L across southern Arkansas (USGS machine-learning study, 2024). Many wells there have more than 100 mg/L, so a typical Smackover brine is far below Atacama, but the USGS notes many wells in southwestern Arkansas already show more than 100 mg/L.

Lithium brine grade and price: what the numbers do to value

Grade, volume pumped and recovery decide how much lithium a brine project makes, and the price of lithium carbonate decides what that is worth. The USGS gives an annual average battery-grade lithium carbonate price of US$63,700 per tonne in 2022, falling to US$11,800 in 2024 and an estimated US$9,000 in 2025 (real dollars, USGS, 2026). A lower price squeezes high-cost, low-grade brines first, which is one reason a 160 ppm pond operation and a 1,400 ppm one respond so differently.

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US battery-grade lithium carbonate price

US$ per tonne, annual average in real dollars

The calculator below turns a brine grade into tonnes of lithium and lithium carbonate equivalent (LCE). It uses plain arithmetic: 1 mg/L equals 1 g/m³, and 1 tonne of lithium makes 5.323 tonnes of lithium carbonate (from the molar masses of Li₂CO₃ and 2 Li). Use your own project’s pumped volume, grade and recovery; the defaults are round examples, not benchmarks, and the price is an input you set to today’s market.

Reading a brine assay: from ppm to mg/L to tonnes

A lab report may give lithium in mg/L, in ppm or in kilograms per cubic metre. Convert before you compare. For mass-based ppm, multiply by the brine density in kilograms per litre to get mg/L. A brine that weighs 1.2 kg per litre would turn 1,400 ppm into about 1,680 mg/L; the density is an illustration, so use the measured value for the brine in question. One mg/L is the same as one gram per cubic metre, so a cubic metre of brine at 1,000 mg/L carries 1 kg of lithium.

Worked example with round numbers: pump 10 million cubic metres of brine in a year at 1,000 mg/L and the brine holds 10,000 tonnes of lithium. If the plant recovers 50% of it, that is 5,000 tonnes of lithium, or about 26,600 tonnes of lithium carbonate equivalent at the 5.323 factor. At an example price of US$10,000 per tonne, the output would be worth about US$266 million a year before costs. Change any of those inputs in the calculator to see how sensitive the answer is; recovery and price move the result as much as the headline grade does.

Two checks save time. First, ask whether the grade is an average over the whole brine volume or a few best wells. Second, ask whether the resource is the lithium in place or the share that can be pumped, since drainable porosity limits the second. The USGS Arkansas estimate explains exactly this limit: its range reflects model uncertainty and the range of porosity, and it counts lithium in place, not what can be extracted.

Brine compared with hard rock, clay and geothermal lithium

The USGS says lithium is found in some igneous rocks and clay deposits and is dissolved in subsurface brines (USGS Fact Sheet 2024-3052). In its US resource count, measured and indicated lithium comes from continental brines, claystone, geothermal brines, hectorite, oilfield brines and pegmatites, totalling 30 million tonnes in the United States (USGS, 2026). Hectorite, a lithium clay, holds about half a percent lithium (USGS, 2017).

The practical difference is the exploration method. Brine projects are tested by drilling wells, pumping and sampling, and judged on brine volume, grade and chemistry. Hard-rock projects are judged on ore tonnes and grade in rock. A reader holding ground in a dry basin should therefore ask first whether the basin is closed, whether it holds brine at depth, and who holds the surrounding water rights, before comparing it with a pegmatite project.

Water, land and community points around salars

Water is the issue most often raised about salars. The Nature Reviews paper frames evaporation as questioned for its intensive water use, long duration and limitation to continental brines, and says the fresh water use of DLE needs quantifying. The Argentine comparison above shows a trade-off rather than a winner: less brine consumed at the DLE site, more fresh water. Local aquifers also matter, because the studied projects draw fresh water from rivers and aquifers around the salt flat.

Agreements are changing too. The Codelco and SQM structure for the Salar de Atacama followed an Indigenous consultation process led by Corfo, and runs under existing contracts and new ones from 2031 (Codelco, 2025). For a licence holder or investor, consultation and water terms are part of the project risk, not a footnote to the geology.

▶ A claymation overview of seven environmental impacts of mining, with satellite maps. · 2:31

How satellites help screen brine ground

Satellites cannot measure lithium in brine under a salar; only sampling from wells and boreholes can do that. They can map the surface things that go with brine basins. The USGS Basin and Range study ranked playas by size, source rocks, vegetation as a sign of water, known prospects and ASTER-derived alteration products, which shows how a regional screen can be built before anyone drills (USGS SIM 3554). Landsat images were enough to spot buildings and evaporation ponds appearing at the southern end of the Salar de Uyuni from 2011 (NASA).

For a consultant weighing a licence in a salar or playa, a satellite mineral detection screen is a quick way to see basin extent, surface salt crust, existing ponds and nearby disturbance before field costs begin. Results are exploration targets, not a resource estimate, and brine grade still has to come from sampling. To scope a site, use the mining query form.

▶ A two-minute explainer on what remote sensing for mining measures and where it stops. · 2:01

What to check before you buy into a brine project

• The unit: mg/L, ppm and kg per tonne are not interchangeable. Ask for the density used.
• Average or peak: a single high sample says little. Look for the average grade across the volume that is claimed.
• Magnesium to lithium ratio: a high ratio, as at Uyuni, raises processing cost.
• Drainable porosity: the share of brine that actually flows to a well decides how much of the resource can be pumped. The USGS notes its Arkansas range depends on porosity assumptions.
• Water rights: brine and fresh water both matter, and the Argentine comparison above shows DLE can shift the need to fresh water.
• Ownership and consultation: state partnerships and Indigenous consultation shape who can operate, as the Chilean agreements show.
• The technical report: check that the recovery number is from pilot data on the real brine.

Frequently asked questions

What is a lithium brine pool?

It is usually a shallow, lined evaporation pond where lithium-rich brine pumped from a salt flat is concentrated by the sun. It can also loosely mean the brine reservoir under the salar. It has no link to the brine pools on the deep ocean floor.

What is lithium brine?

Lithium brine is very salty groundwater with dissolved lithium, trapped in closed basins or deep sedimentary rocks. The USGS reports average grades from about 160 ppm at Clayton Valley to about 1,400 ppm at the Salar de Atacama.

How is lithium extracted from salt flats?

Wells pump brine into a series of evaporation ponds. Over roughly 6 to 24 months, depending on climate and brine, water evaporates and other salts drop out, leaving a lithium-rich liquor that a plant converts to lithium carbonate or hydroxide.

How long does brine take to evaporate?

NASA reports about six months in the pools at Uyuni, a peer-reviewed study of two Argentine projects cites 12 to 18 months as typical, and the USGS says nearly 2 years at Clayton Valley.

What is a good lithium brine grade in mg/L?

There is no single cut-off, since it depends on magnesium, recovery method, scale and price. For reference, the USGS averages are 1,400 ppm at Atacama, 700 ppm at Zabuye, about 320 ppm at Uyuni and about 160 ppm at Clayton Valley.

Where are the biggest lithium brine deposits?

The Andean salars in Chile, Argentina and Bolivia, plus Tibet and Qinghai in China. The USGS puts Argentina’s lithium resources at 28 million tonnes, Bolivia’s at 23 million and Chile’s at 13 million, all deposit types included.

Is direct lithium extraction better than evaporation ponds?

It aims to avoid brine evaporation, and some methods recover above 95% in tests, but it can need more fresh water, and only 30% of tests used real brine (Nature Reviews, 2022). Which is better depends on the brine and the site.

Are there lithium brines in the United States?

Yes. Nevada has a producing brine operation, and Arkansas holds an in-place estimate of 5.1 to 19.0 million tonnes of lithium in Smackover brines (USGS, 2024), which has not been shown to be economic.

Why is Salar de Uyuni not a big producer?

NASA points to cooler, wetter weather that slows evaporation and to high magnesium and potassium in the brine, which raise processing cost. Bolivia has not been among the top producers.

Can satellites find lithium brine?

They can map salars, playas, ponds and surface alteration, helping rank ground. Brine grade itself needs well sampling.

Who operates the Salar de Atacama lithium now?

Codelco and SQM completed the NovaAndino Litio joint venture in December 2025 for the Salar de Atacama, with the plan running to 2060.