A mineral is a naturally occurring solid that has evolved through a geological process. It must have a specific chemical composition and a distinctive internal crystal structure. All of the rocks that make up our planet are minerals.
In order for a substance to be correctly classified as a mineral it must have formed naturally without any human intervention, it should not droop, melt or evaporate and should be inorganic meaning it's not a carbon compound (a chemical substance which contains carbon) like all living things on Earth.
For a mineral to be crystalline the atoms must be arranged in a regular, geometric, three-dimensional pattern which forms a solid body known as a crystal.
Although there are more than 4000 minerals which have been identified only about 100 are common.