Tough 1(R) Himalayan Rock Salt Tough 1(R) Himalayan Rock Salt is 100% all natural, and comes straight from the Himalayan Mountains. It's a great source of iron, potassium and magnesium, all of which are for maintaining your horse's health. It is rock hard and difficult for horses to break chunks off, so it's safe to be left out for horses. Because it's much more weather-resistant than other salt licks, it will last longer. Includes rope.