Quartz

Quartz is one of the most abundant forms of rock in the Earth's crust, exceeded only by Feldspar. Quartz can be a beautiful rock, and some forms are considered semi-precious gems. It is a silicate made up of Silicon  and Oxygen (SiO2).

While this igneous rock is highly deposited all around the world, a particular high concentration of it can be found on the inland, and both coasts of Brazil.