Rocks, Minerals and Soil (continued)

  • O granite (comes from Latin granum(meaning 'grain') is formed inside the earth's crust by slow cooling and solidification of the magma. It is widely used to coat floors, walls and sinks. Granite is made up of grains of various colors and sparkles: they are minerals.

The minerals that form granite

A rock is formed of one or more minerals. Most rocks are made up of various types of minerals. Minerals are elements or chemical compounds, usually solid, found naturally on the planet.

There are over two thousand different types of minerals. They are formed by the union of various types of atoms, such as silicon, oxygen, aluminum, calcium and iron. The differences between minerals are due to the different types of atoms that form them and also to the way the atoms are "arranged".

Piece of granite

Granite is used to make sinks, floors, etc.

Granite is mainly made up of three types of minerals: quartz, O feldspar and the mica.

Grains that appear gray in the granite correspond to grains of quartz. See in the figure below that quartz, like most minerals, is made up of a series of parts that resemble geometric figures. We then say that quartz, like most minerals, forms crystals.

Rhinestone formed by a variety of transparent quartz. See above the typical crystalline form of this crystal. There are also colorful quartz shapes, such as amethyst.

The other type of mineral present in granite is feldspar, which can have different shades: yellow, white, pink, green.

Decomposition of this mineral by rainwater forms the clay which is used to make bricks, cement, concrete and various objects.

The bright black or dark gray color present in the granite corresponds to small grains of mica. There are also other types of mica, of different colors. Mica is a good heat insulator of electricity; This is why it is used in the electric iron.