One of the first steps in studying a group, such as minerals, is to subdivide them according to similiarities they may have with one another. This is called classification. Minerals are classified according to chemical composition. There are seven major chemical groups (see the headings at the left). There are also several minor groups, these include the sulfosalts, nitrates, borates , tungstates and molybdates, and the phosphates, arsenates, and vanadates. To get to an individual mineral one would first look at the chemistry which in turn may be divided into crystal structure groups. A group is made up of species, which may have several varieties.