Rock Salt is a granular naturally occurring mineral known as sodium chloride (halite) with a low freezing point. Gathered from deposits it can be utilised as a gritting product for roads and surfaces domestically and commercially to manage ice. When water is added in the form of rain, snow or ice a brine is created which has a lower freezing point than water alone. On ice, it will cause it to melt.
It can also be used as a strong weed killer in water, but care should be given as in high quantities it will also kill plants as it spreads through the soil.