Every mineral type contains defined amounts of specific molecules in its structure. Most minerals are composed of molecules that contain an exact amount of certain atoms. For example, every water molecule contains two hydrogen atoms and one oxygen atom. Grouped water molecules form bodies of water. Minute amounts of other molecules mixed among the water molecules are known as impurities .
Impurities can slightly alter physical properties such as color.
Chemical Formula 92 elements occur naturally on earth. Most are very rare. Each mineral has a unique arrangement and the number of elements contained in its crystal structure . This arrangement of atoms determines a mineral type. All minerals have a chemical formula , which is an analysis of the types and amounts of elements present in a mineral.