bath salt in bulk

Bulk rock salt for baths?
Hello, where can I get bulk rock salt that is pure enough to put in baths?
I get it from the supermarket but in small contrainers, and it would be more economical to get a big sack of it…. I notice you can get de-icing rock salt for cheap at varying levels of purity… The purest being called “white” … However, is this pure enough to be used in the bath (and hence on your skin) ?
I am wondering if these de-icing rock salts have additives or whatever….
Please help,
Thanks.
Don’t, salt is very drying on the skin, and will age you prematurely. it is not at all moisturising.
