There is plenty of magnesium elsewhere. China just sells it a bit cheaper than other places. It wouldn’t take long to ramp up production elsewhere if there were any competent world leaders around. But with the US now dominated by anti-mining eco-loonies we are probably screwed.
China has been buying up mines all over the world...apparently the Russians, too. Both bought into Guinea’s bauxite mines and had a puppet in place there until recently. Guinea’s military staged a coup and threw him out, not sure for how long...turns out Russiagate’s Oleg Deripaska had or has his aluminum company Aleus there. Speaking of the aluminum business, wasn’t that pardongate’s Marc Rich’s thing, too?
Magnesium is not mined...it is extracted from seawater, and has been since WWII. Dow Chemical perfected the process, and as of 1995, their production facility in Freeport, TX was still up and running.