The Earth has a layered structure made up of the core, the mantle and the crust. Different elements are present in different parts of the Earth’s structure. The crust is made from enormous ...

Geologists can tell a chalcedony from the arrangement and structure of its crystals. Photograph by blickwinkel/Alamy Rocks themselves are made of clusters or mixtures of minerals, and minerals and ...

Petrology is the study of rocks - igneous, metamorphic, and sedimentary - and the processes that form and transform them. Mineralogy is the study of the chemistry, crystal structure and physical ...