What is the full name of Mg2So4?

MgS2O3 is magnesium thiOSulfate;

It's a ternary compound, a metal bonded with a polyatomic ion. The metal has a fixed cation. List the cation-- magnesium-- and find the name of the polyatomic ion. S2O3 is thiOSulfate, so the full name would be: Magnesium ThiOSulfate.