Minerals and rocks / Минералы и горные породы

The solid part of the Earth is made up of rocks. Rocks are made up of minerals. A mineral is a naturally
occurring inorganic solid. It has a specific chemical composition and a characteristic crystal structure.
Quartz is a very common mineral. Most beach sand is composed of quartz. It has the composition SiO2
and forms elongate 6-sided crystals that terminate at a point <...>