There is an almost endless list of rocks, minerals and gems but geologists are scientists who like to makes things as simple as possible and they like to classify everything into simple groups.  It is more important to a geologist to look at a rock in fine detail, understand how it formed and what it is made from that to give the rock a name.  By know how a rock formed, we can often tell a lot about the environment, the tectonic processes, the history and relationship of the rock to other rocks in the area. 

A Rock is a natural material composed of one or more minerals. A mineral is a solid, naturally occurring substance composed of one or more elements. ​A gem is a precious or semi-precious mineral which has been cut and polished.   

For example - The mineral known as beryl is composed of the elements Beryllium, ​Aluminium, Silica and Oxygen and is found in some igneous and metamorphic rocks. Some examples of beryl are gem-quality and we know them as emeralds.  

This section covers:

• The 3 rock types - Igneous, Sedimentary and Metamorphic.
• The rock cycle​​​
• How old are rocks?