$24M Later, Magrathea Eyes U.S. Magnesium Boom

Magrathea raised $24M and partnered with TETRA to pull magnesium from seawater, aiming to loosen China's grip on a critical metal.

30 Jun 2026

Magrathea, a US start-up, has raised $24m in a Series A funding round and formed a joint venture with chemicals group TETRA to produce magnesium from seawater on a commercial scale. The new entity, Arkansas Magnesia, will apply Magrathea's electrolysis process, which extracts the metal directly from seawater rather than through conventional smelting.

The push centres on the automotive industry. Magnesium weighs roughly a third less than aluminium, a property that has made it attractive to carmakers trying to cut vehicle weight and stretch the range of electric models. Most US supply currently comes from abroad, chiefly China, leaving manufacturers exposed to trade disruption and price swings.

Arkansas Magnesia is designed to address that dependence. Magrathea brings the extraction technology; TETRA brings experience in chemical manufacturing. Together, the two companies hope to scale output to commercially significant volumes, a step that has eluded earlier attempts at domestic magnesium production.

Demand pressure has built quickly. Carmakers expanding electric vehicle lines need lighter components, and procurement teams are placing greater weight on supply chains that are traceable and based at home. A reliable domestic source could shorten delivery times and reduce price volatility for manufacturers further down the chain.

For now, the venture remains in its early stages. Whether Arkansas Magnesia can move from pilot output to volumes that matter for the broader auto industry is the question that will determine its significance. Policymakers keen to reduce reliance on imported critical materials will be watching the venture's progress, as will rival producers assessing whether seawater extraction can compete with established smelting routes on cost.