Rock salt or halite is a mineral the contains sodium chloride (table salt) as well as other minerals and impurities. You can remove most of these contaminants using two simple purification techniques: filtration and evaporation.
Materials
Rock salt
Water
Spatula
Filter paper
Funnel
Evaporating dish
Beaker or graduated cylinder
Tripod
Bunsen burner
Filtration
If the rock salt is one large chunk, grind it into a powder using a mortar and pestle or a coffee grinder.
Add 30-50 milliliters of water to six heaping spatula scoops of rock salt.
Stir to dissolve the salt.
Place the filter paper in the mouth of the funnel.
Place the evaporating dish under the funnel to collect the liquid.
Slowly pour the rock salt solution into the funnel. Make sure you don't over-fill the funnel. You don't want the liquid to flow around the top of the filter paper because then it isn't getting filtered.
