text: You'll need a hammer, a filter and something to boil water in.\n\nYou'll want to pulverise the rocksalt, leave it in water for the salt to dissolve (hot water will speed up the process).. filter it to remove the rock and then boil off the water to leave salt.\n\nI wouldn't recommend actually doing this with random rocks that contain salt to produce salt for consumption.. there will almost certainly be other water soluble materials in there that you wouldn't want to eat.