Rocks, like minerals,also have properties and characteristics that will allow us to classify them. These properties depend on how the rock originated.
Depending on how the rock is found in the field, its arrangement in horizontal, inclined, curved layers, etc., in large solid blocks, etc., it can give us information about the origin of that rock and its classification.
Rocas sedimentarias. Estratos verticales en Aliaga (Teruel)
The rock is composed of all the minerals that form it. Depending on the minerals it contains, it will be classified as one rock or another. According to their composition, these types of rocks are distinguished:
- Simple and homogeneous rocks. The rock is made up of a single type of mineral, such as limestone rock, made up of grains of the mineral calcite.
- Composite or heterogeneous rocks. Rocks made up of various types of minerals, such as granite, which is made up of quartz, feldspar, and mica.
Organogenic rocks (coal, oil) are of organic and not mineral origin. Coming from the remains of plants and animals, they are not made up of minerals and could not be classified in any of the above groups.
There are rocks that can be found in nature with the same shape, with a similar composition, but with a different texture.
Texture is the way the grains of minerals are arranged, whether they are disordered or ordered, how they are arranged, size of the grains, etc.