What are rocks and minerals?
Rock are natural aggregates or combination of one or more minerals. Some rocks, such as quartzite (pure quart) and marble (pure calcite) contain only one mineral. Most, however, consist of more than one kind. Minerals are naturally occurring inorganic solids with definite chemical compositions and an ordered atomic arrangement. Here, two common rocks – granite and basalt – are shown along with individual specimens of the major minerals of which they are formed. Rock-forming minerals can be divided into several groups – these are described in more detail on pages 42-43.