Concept in Definition ABC

In the sphere of the geology The word stone is not used, but two terms are used: rock or mineral. Rocks are formed after a process geological and they are made up of one or more minerals. Minerals are made up of chemical elements.

The rock masses that cover the planet's surface are made up of one or more minerals. Rocks are divided into three groups according to their origin: sedimentary, metamorphic, and igneous.

Formation, types and texture

Igneous rocks make up 90% of the Earth crust and they are formed by minerals that belong to the group of silicates (this group is divided into ferrogmagnesians and non-ferromagnesians, which indicates that the rock contains iron or not). The word igneous is used for its description because this word means fire in Greek.

Igneous rocks are those that are formed after the magma cooling process. Thus, the magma from volcanic activity reaches the land surface and finally solidifies. These rocks are subdivided into two distinct groups: plutonic or inclusive and volcanic or extrusive. The former are formed from a slow cooling process of the magma that comes from the interior of the earth's crust (granite, diorite and peridotite stand out in this group). Those of the volcanic type are formed from a rapid cooling process that takes place on the surface (among them is rhyolite, basalt or dacite).

When magma has solidified, large crystals are created. In this sense, the slower the cooling process, the larger the size of the igneous rock. In the case of rapid cooling, instead of glass, glass is formed.

Granite is the best known igneous rock

Granite has formed over the last 300 million years and is the direct consequence of the cooling process of magma. This circumstance makes the granite present large crystals that are visible to the naked eye. This rock is found on the earth's surface due to erosion that has taken place over the past 100 million years.

Large blocks are extracted from the mines, which are processed into smaller pieces. The crystals inside are evenly distributed.

Its final finish is carried out through a polishing procedure that removes the porosity of the original rock. This type of igneous rock has been and is highly valued as a material for building, both for the interior and exterior of the buildings. It is an elegant and attractive material and is especially valued because it does not need a maintenance special.

Fotolia photos: Espy3008 / Markus