1. 
   Rock salt
   A large crystal form of salt that is mixed with cracked ice to freeze ice cream.
   Found op http://www.chowbaby.com/10_2000/glossary/glossary.html?synchpage=22&Z=75017
   
   
2. 
   rock salt
   rock salt: see sodium chloride.
   Found op http://www.infoplease.com/ce6/sci/A0918204.html
   
   
3. 
   rocksalt
   1) Halite 2) Ice breaker? 3) Snow-melting stuff
   Found op http://www.mijnwoordenboek.nl/EN/crossword-dictionary/rocksalt/1
   
   

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