MoM is magnesium hydroxide, not mag sulfate.
http://www.webmd.com/drugs/2/drug-326/milk-of-magnesia-oral/details
https://www.phillipsdigestive.com/products/milk-magnesia/
https://en.wikipedia.org/wiki/Magnesium_hydroxide
http://www.webmd.com/drugs/2/drug-326/milk-of-magnesia-oral/details
https://www.phillipsdigestive.com/products/milk-magnesia/
https://en.wikipedia.org/wiki/Magnesium_hydroxide