I'll echo the same message others are saying: If you feel an urge to put rocks in your mouth, your gut might be trying to tell you that you have a mineral defficiency. Take a look at your diet and see if there's something missing, and find out what you can eat to restore it. You don't need a salt lick (what the fuck?), but mineralized water could be helpful. Whatever you do, don't put rocks in your mouth. They'll fuck up your teeth and gums and most likely have parasites, bacteria, or molds on them.