Researchers at Pacific Northwest National Laboratory are developing a way to recover magnesium from seawater, a potential new source of a mineral used in manufacturing and other industries. The team plans to test its system at the lab’s facility on the Washington coast. The process brings seawater into contact with a separate stream containing dissolved sodium hydroxide, commonly known as lye. The reaction forms magnesium hydroxide, which separates from the water and sinks. That material can be used in products including ceramics, steel and fire-resistant building materials, or processed further into magnesium metal. Magnesium is the most abundant mineral in seawater after sodium and chloride. PNNL estimates that an Olympic-size swimming pool of seawater contains more than 6,500 pounds of it. The researchers say their process could potentially be installed at existing desalination plants, where seawater is already processed to produce drinking water. Chemical oceanographer Jessica Cross, part of the PNNL team, said in a statement that a small fraction of the ocean’s water contains enough critical minerals, including magnesium and lithium, to meet human needs for tens of thousands of years. That estimate reflects the immense volume of seawater; extracting minerals at useful scale remains a technical challenge. The current system targets magnesium. The broader interest in seawater reflects concern over supplies of critical minerals, a U.S. government designation for materials considered important to the economy or national security. Magnesium and lithium are used in products such as batteries and electronics, and domestic supplies of some critical minerals are limited. The planned coastal test will help researchers assess the magnesium process beyond its development work in the lab. Its usefulness will depend on whether it can recover the mineral efficiently and economically, and how it performs alongside the other demands of seawater processing.