Only just read through this thread, may have to try the crystal deodorants.
Wanted to mention (as I can't see it so far) that I've been using magnesium oil (magnesium chloride) in a spray bottle in the mornings all over my body....sometimes I'll wash it off, sometimes I'll leave it on for the day (my skin seems to have gotten use to it, no itching).
One thing I have noticed is that it does seem to work as a deodorant (a quick search of the internet and others report this too). Be warned however that magnesium chloride should be used with extreme caution on sensitive parts of your body, or cut/shaved areas (if you shave your under arms for example)....it stings like heck!
If its not a problem putting it on your underarms (i.e. no stinging or itching) the only down side I've noticed is occasionally smelling like a swimming pool!
Actually...thinking about the reaction between chlorine and biological organisms (i.e. that strong chlorine/swimming pool smell)...it may not be such a good idea, as it may be creating chlorine gas (even if in small quantities).....not sure.