The initial process for precipitating Mg(OH)2 from seawater was in France in the 19th century but now exists in China, Israel, and the US.

The first patent for precipitating Mg(OH)2 from seawater was in 1943.

Synthetically produced magnesium hydroxide became a popular alternative to caustic soda and lime as a wastewater treatment additive in the late 1980s and early 1990s.

Synthetic magnesium hydroxide accounts for nearly 60% of the international supply.

It is significantly more complicated to produce and requires rigorous testing to ensure quality.