Salt may be the first mineral that comes to mind when we think about seawater, but in every drop, there are actually dozens of elements and compounds. Calcium, silicon, copper, uranium and even silver and gold are all there, albeit in trace amounts.

Given the sheer volume of the oceans, even trace amounts could add up to significant quantities — if we could get them out of the water.

“Just 0.1 percent of seawater contains enough critical minerals like magnesium and lithium … to meet humanity’s needs for the next 50,000 years or more,” chemical oceanographer Jessica Cross said in a release.

Cross is part of a team at Pacific Northwest National Laboratory working to find ways of extracting them.

Magnesium and lithium are considered “critical minerals,” a political definition given to elements and minerals considered essential for the U.S. economy or national security. They’re often important for manufacturing items like batteries and electronics — and many are not readily available in the United States. The Trump Administration is putting more than a billion dollars behind securing domestic supplies.

After chloride and sodium, magnesium is the most abundant mineral found in seawater. An Olympic-size pool of ocean water contains more than 6,500 pounds of the element, according to the lab.

The PNNL researchers have created a system to extract magnesium from seawater. They run a stream of ocean water alongside a stream of dissolved sodium hydroxide — an extreme base commonly known as lye. Where the liquids meet, magnesium hydroxide solidifies and sinks out of the water.

This magnesium hydroxide can be further processed into magnesium metal, or it can be used as-is in environmental cleanups, ceramics and steel production, as an ingredient in fire-resistant construction materials, or even for medical needs (it’s the active ingredient in Milk of Magnesia, a common antacid and laxative).

The researchers say the system could be easily installed at existing desalination plants where seawater is processed into drinking water.

The lab is planning to test the system at their lab on the Washington Coast.

In these All Science Snapshots, “All Science. No Fiction.” creator Jes Burns features the most interesting, wondrous and hopeful science coming out of the Pacific Northwest.

Find full episodes of “All Science. No Fiction.” here.

News Source : https://www.opb.org/article/2026/10/15/northwest-researchers-mining-seawater-motherlode-critical-minerals/