Rocks and minerals

Rock formation

Geology is the science that focuses on studying the composition of the earth's crust in which we can find rocks and minerals. There are different types of rocks in the world according to their characteristics, origin and formation. The same goes for minerals. We can extract valuable natural resources from rocks and minerals, which is why their study is of great importance.

For this reason, we are going to dedicate this article to tell you everything you need to know about rocks and minerals, what are their main classifications and importance of our planet.

Rocks and minerals

minerals

Definition of mineral

The first of all is to know the definition of mineral and rock in order to establish a basis and be able to explain the rest. Minerals are made up of solid, natural and inorganic materials derived from magma. They can also be formed by changes in other existing and formed minerals. Each mineral has a clear chemical structure, which depends entirely on its composition. Its formation process also has unique physical characteristics.

Minerals have ordered atoms. These atoms have been found to form a cell that repeats itself throughout the internal structure. These structures produce certain geometric shapes that, although not always visible to the naked eye, do exist.

The unit cell forms crystals that clump together and form a lattice or lattice structure. These crystals mineral formers are very slow. The slower the crystal formation, the more ordered all the particles are and, therefore, the better the crystallization process.

The crystals are forming or growing depending on the axes or planes of symmetry. The crystalline systems are grouping the 32 kinds of symmetry that a crystal can have. We have some of the main ones:

  • Regular or cubic
  • trigonal
  • Hexagonal
  • Rhombic
  • Monoclinic
  • Triclinic
  • tetragonal

Classification of minerals

Rocks and minerals

Mineral crystals they are not isolated, but form aggregates. If two or more crystals grow in the same plane or axis of symmetry, it is considered to be a mineral structure called a twin. An example of a twin is crystalline rock quartz. If the minerals cover the surface of the rock, they will form clumps or dendrites. For example, pyrolusite.

On the contrary, if the minerals crystallize in the rock cavity, a structure called geodesic is formed. These geodes are sold all over the world for their beauty and decoration. An example of a geode can be olivine.

There are different standards for classifying minerals. According to the composition of the minerals, it can be classified more easily. They are divided into:

  • Metal: Metallic mineral formed by magma. The most famous are copper and silver, limonite, magnetite, pyrite, sphalerite, malachite, azurite or cinnabar.
  • Non-metallic. Among the non-metals, we have the silicates, whose main component is silicon dioxide. They are made up of magma in the asthenosphere. They are minerals like olivine, talc, muscovite, quartz and clay. We also have mineral salt, which is formed from the salt that precipitates when ocean water evaporates. They can also be formed by recrystallization of other minerals. They are minerals formed by precipitation. For example, we have calcite, halite, silvin, gypsum, magnesite, anhydrite, etc. Lastly, we have other minerals with other components. These have been formed through magma or recrystallization. We find fluorite, sulfur, graphite, aragonite, apatite and calcite.

Characteristics and types of rocks

Minerals and rocks

Rocks are made up of minerals or aggregates of individual minerals. In the first type, we have granite, and in minerals, we have rock salt as an example. Rock formation is a very slow process and follows a different process.

According to the genesis of the rocks, they can be divided into three types: igneous rocks, sedimentary rocks, and metamorphic rocks. These rocks are not permanent, but are constantly evolving and changing. Of course, they are changes that occurred during geologic time. In other words, on a human scale, we won't see rock forms or complete self-destruction, but rocks have a so-called rock cycle.

Igneous rocks

Igneous rocks are rocks formed by the cooling of magma inside the earth. It has a fluid part of the mantle called the asthenosphere. Magma can be cooled in the earth's crust or it can be cooled by the force of the earth's crust. Depending on where the magma is cooled, the crystals will form at different speeds in one way or another, resulting in various textures, such as:

  • Granulated: When magma slowly cools and minerals crystallize, very similarly sized particles can be seen.
  • Porphyry: magma is produced when it cools at different times. At first it started to cool slowly, but then it gets faster and faster.
  • Vitreous. It is also called porous texture. It occurs when magma cools rapidly. In this way, the crystals do not form, but have the appearance of glass.

Sedimentary rocks

They are made up of materials eroded by other rocks. These substances are transported and deposited on the bottom of rivers or oceans. When they accumulate, they produce formations. These new rocks are formed through processes such as petrification, compaction, cementation and recrystallization.

Metamorphic rocks

They are rocks formed from other rocks. They are usually made up of sedimentary rocks that have undergone physical and chemical transformation processes. It is geological factors such as pressure and temperature that are changing the rock. Therefore, the type of rock depends on the minerals it contains and the degree of transformation it has undergone due to geological factors.

There are numerous metamorphic processes that cause rocks to change and evolve. For instance, sudden differences in temperature are called thermoclastito. It is a process in which sudden differences in temperature between day and night, as occurs in deserts, can cause the formation of cracks and physical destruction of a rock. The same occurs with erosive processes caused by both wind and water. Wind erosion or the processes of freezing and thawing of water in which cracks in the rocks can end up causing them to metamorphose.

I hope that with this information you can learn more about rocks and minerals.


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