From what I can find with a quick search, Mg Oxide mixed with water becomes Mg Hydroxide, so it seems it would probably be fine, but I am not sure if it would impact percentages used. Some folks on the web mention using Mg Chloride in DIY deodorants, but I would be concerned with absorbing additional salt through the skin. I suppose if you are not on a salt restricted diet for medical reasons it may not matter to you, but for some folks it may.Still working through the thread, but a question about the type of magnesium. I can get/have oxide or chloride much more readily than hydroxide. Would they also be options to use?