In reply to Hibachi:
> (In reply to kdr001) I've heard that it is a laxative but never been sure if it's true.
In the early '80s the word was that there was genuine concern expressed by the Sheffield health authorities at the sudden massive increase in sales of 'light magnesium carbonate', which at the time was only sold in chemists for the treatment (apparently taken orally) of constipation. Until someone cottoned onto the fact that climbers had discovered its sweat-absorbing benefits! It wasn't until a year or two later that climbing shops started selling it.