Neptune Energy is Producing Brines from the Rotliegend Sandstone in Germany’s Altmark Basin with Lithium Concentrations Rivalling the U.S Smackover Formation

     The Saxony-Anhalt plains in Germany are the site of a new lithium-rich brine find. Extracting lithium from sedimentary basin brines is gaining traction as new direct lithium extraction (DLE) methods are being rolled out. Natural gas was once the main product of the Altmark Basin, where lithium has been found in high concentrations in the Rotliegend Sandstone at true vertical depths of about 3200 to 4000 meters (about 10,000-12,000 ft). An average lithium concentration of 375 milligrams per litre (mg/L) makes the find economically important for brines. Daily Galaxy notes that:

“Geothermal gradients in the region exceed 120°C, which supports both mineral dissolution and potential co-production of heat during extraction. This combination may improve project economics and environmental performance.”

     Neptune Energy is operating the project. Resource assessments provided by independent assessor Sproule ERCE estimate a lithium resource of 43 million tonnes of lithium carbonate equivalent (LCE). That would make the Altmark field one of the largest lithium resources in the world from a single site.

     In addition to drilling, the company is pilot testing different methods of DLE. One is utilizing ion exchange for extraction, and another is utilizing adsorption. They are also testing membrane methods. These DLE methods do not use evaporation ponds and are considered much more environmentally benign than the ones that do.

     A paper presented at the European Association of Geoscientists & Engineers explains the source of the lithium as mica-rich volcanic clasts in the sandstone. The lithium was leached out over millions of years, aided by hot hydrothermal water.

     (As an aside, I heard recently that lithium-rich groundwater in the Netherlands that is consumed as drinking water correlates strongly to a reduction in Alzheimer’s disease in the region.)

     The project is in an industrial area and can utilize some of the pre-existing gas field infrastructure. This should aid project economics. The next phase of the project is a larger demonstration plant. DLE methods still need economic improvement. Regulators are assessing groundwater impacts, waste management, and long-term sustainability.

     Neptune Energy was purchased by the Italian Oil & Gas multinational company Eni in 2024. 

     Below are a timeline, a project image, and a depiction of the process.

     According to Neptune Energy’s website:

“If scaled up commercially, up to 25,000 tonnes of lithium carbonate could be produced annually - enough to supply around 500,000 electric cars per year with battery material and make Germany less dependent on imports of raw materials. Our project contributes directly to the goals of the German government's raw materials strategy, which calls for a strengthening of domestic raw materials security and extraction.”

     The company is utilizing AI to examine large quantities of geological, gas production, and water sample data from the gas field, which has been in production for over six decades. The depiction seems to show that the lithium brine is downdip from the gas accumulation in the same geological formation.

"The lithium project depends on fast and well-founded decisions. This is where the AI-supported analysis of the Altmark data makes a clear contribution: better models, less uncertainty, faster planning. This gives us a concrete competitive advantage," adds Dr Axel Wenke, Director New Energy at Neptune Energy.

References:

 

43 million tons: Germany confirms one of the world’s largest lithium deposits in former gas field. Arezki Amiri. Daily Galaxy. January 6, 2026. 43 million tons: Germany confirms one of the world’s largest lithium deposits in former gas field

Findings on the Origin of Lithium Enrichment in Brines in the Altmark Gas Field Area, Germany. J. Böcker. European Association of Geoscientists & Engineers. 86th EAGE Annual Conference & Exhibition, Jun 2025, Volume 2025, p.1 – 5. Findings on the Origin of Lithium Enrichment in Brines in the Altmark Gas Field Area, Germany | Earthdoc

AI project makes analogue data treasures fit for the future of raw materials. 17 Dezember 2025. Neptune Energy. AI project makes analogue data treasures fit for the future of raw materials

Lithium extraction in the Altmark. Neptune Energy. Lithium extraction Altmark