Magnesium hydroxide (milk of magnesia)
Magnesium Hydroxide
Used in natural deodorants to neutralise odour-causing bacteria.

How solid is the pore-clogging number
Magnesium hydroxide (milk of magnesia) rates 0 of 5 — no observed follicular occlusion in testing. The rating is graded moderate. Reasonably supported, but from fewer or less direct sources than the best-established ratings.
It describes the raw ingredient in isolation. In a finished product, how much is present and where it sits in the list matter just as much. Check a whole label to see it in context.