The Geology of Magnesium: It Is Everywhere, Yet Made in One Place
Magnesium is abundant in dolomite, brines, and seawater itself. Its concentration in production, not resource scarcity, is the real story.
Magnesium is a genuine outlier in this series: there is no realistic scenario where the world runs out of the resource itself, it is the eighth most abundant element in the crust, present in dolomite rock, in evaporite brines, and dissolved in seawater at a known, essentially inexhaustible concentration.
Three real sources, not one
Dolomite, a magnesium-calcium carbonate rock, is the main feedstock for thermal (Pidgeon process) magnesium production, covered on this material’s mining page. Brine deposits, concentrated saline groundwater in closed basins, similar in origin to the lithium brines covered on lithium’s geology page, provide another route, historically significant in places like the Dead Sea region. Seawater itself, at a known and essentially constant magnesium concentration, is a third, technically demonstrated source, used historically at scale in some Western operations before they closed for economic, not resource, reasons.
Why “abundant” did not mean “secure”
Because the resource itself is not scarce anywhere, the concentration documented on this material’s supply chain page is purely a consequence of where production capacity was built and where it survived, not of where the geology happens to be richest. Several Western dolomite-based operations closed over recent decades specifically because they could not compete on production cost with Chinese capacity, a real economic outcome, not a resource depletion story.
Sources: resource abundance and extraction route framing draw on standard economic geology references (USGS Mineral Commodity Summaries); production figures reference the production data elsewhere on this site.