What is a mineral in geology ?
Mineral : definition
A mineral is a natural, homogeneous solid with a defined chemical composition and an ordered atomic structure.
This definition excludes, among others, liquids and gases, glasses, and in general all materials produced by deliberate human action (in particular synthetic minerals), but not organic materials, such as amber. However, there are exceptions to this definition: a liquid (mercury), and certain solidified gels (opal) which do not have an ordered atomic structure are nevertheless considered to be minerals.
This definition excludes, among others, liquids and gases, glasses, and in general all materials produced by deliberate human action (in particular synthetic minerals), but not organic materials, such as amber. However, there are exceptions to this definition: a liquid (mercury), and certain solidified gels (opal) which do not have an ordered atomic structure are nevertheless considered to be minerals.