i was wondering the exact same thing so I took Relle9's advise and found this line by Alchemy&Ashes » Fri Sep 28, 2012
"Salt bars are soaps with added salt and are usually very high in coconut oil, since it will still lather with the salt added. Most salt bars have anywhere from 50-100% salt to oil ratio...so if your oils weigh 48 oz, you could add anywhere from 24 oz - 48 oz of salt. It makes a very hard bar that can be slightly exfoliating or super scratchy depending on the salt grain you use."