These solid salt rock blocks are known as "white gold" to those in that part of the world, Himalayan rock salt is the purest form of salt available on earth. It is mined from ancient deposits deep in the Himalayas, these rock hard salt licks contain many of the valuable minerals your horse needs to promote a healthy balance in the body such as iron, potassium, and magnesium are particularly useful in replenishing electrolytes lost during hard work. It is these minerals that give the Himalayan rock salt its signature rosy color. The centaur Himalayan rock sock is 100% all natural and is literally "rock hard" so it can be left outside. Machined to a brick that fits in most standard 4 lb. Salt lick holders.