Just like vitamins these Minerals are Vital too! Mineral salts contain certain chemical elements. All these elements have particular jobs to do. However these nutrients, that are again only required in tiny amounts are actually elements that are required by organisms to carry out certain defined processes.
For example, calcium (in milk and cheese) is used to keep bones healthy and iron is needed in our blood to form the substance haemoglobin (which helps to transport oxygen around the body)
Hydrogen, Carbon, Oxygen and Nitrogen are the 4 elements that exist in all organic life form. Thus these are obviously required in greater quantities and are not commonly refered to when we talk of minerals.
These salts are used in cell signalling such as muscle activation and sending nerve impulses.