Importance of the Rocks

Roberta Alessandra Pedrasoli
Degree in Biomedicine

Rocks are largely responsible for the evolution of human beings to their current lifestyle. At an economic level, they are widely used in their "raw" state in civil construction, as a source of energy or minerals and metals, however, its immeasurable importance is probably underestimated, since in many cases it has a role support.

Through the use of a type of rock, in this case mineral coal, the first industrial Revolution which progressed towards the use of oil (and all its derivatives) today. Also, thanks to the rocks we have underground water systems through which it is possible to supply drinking water to almost half of the world's population. Not to mention the exploration of minerals and metals that, for the most part, are embedded in the rocks.

Their study is also relevant, since the lithosphere, better known as the earth's crust, is basically made up of rocks. In fact, the planet earth is basically a big rock in different states, since just below the crust is the mantle. Responsible for 80% of the planet's volume, the mantle is a pasty mass that, when cooled, forms the predominant igneous rocks. Studying them provides us with valuable information about the terrestrial structure, as well as its variation over the years.

However, to understand the role of rocks for the planet and for our life, it is important to know what they are and their different types, as we discuss below.

What are they, how are rocks formed and classified?

The natural combination of minerals in nature gives rise to a solid aggregate called rock. Its classification is based on the proportion of each mineral present in its structure. For example, basalt is basically made up of silicon, aluminum, and iron. Granite is made up of quartz, feldspar, and mica.

The process and environment of formation of the rocks allows us to divide them into three large groups: magmatic or igneous rocks (formed by magma), rocks sedimentary rocks (formed by the precipitation of chemical and organic compounds) and metamorphic rocks (formed by the decomposition of other rocks).

From these three groups arise several subgroups of rocks whose mineralogical composition (minerals, organic compounds and glassy material) is the basis for their classification. The essential minerals will define its nature and the accessory minerals will serve to name the different varieties. A very illustrative example is quartz whose accessory minerals originate stones such as amethyst, crystal, citrine, agate, onyx, among many others. Also, there are rocks of "almost pure" composition, that is, formed from a single mineral and known as monominerals. What differentiates this type of rock from a mineral is its volume, since they appear in nature in large areas of land or in the form of a hill.

Civil construction

Since prehistoric times, man has been looking for ways to understand and explore rocks. The evolution of the way of life of civilizations is related to the improvement of its use. The houses initially made with mud evolved into large constructions such as the pyramids (built with limestone rocks) and Greek temples (Marble) and later the creation of concrete by the Romans (physiochemical transformation of the rocks).

Currently, widely used in civil construction, the following stand out: slate, granite, marble, clay, limestone and basalt. They are usually taken from nature in its raw state and shaped according to its use.

– Slate: Metamorphic rock originated from clayey rocks and used mainly in floors and coatings. Also, it can be used on countertops as it has low absorption and high heat resistance.

– Granite: They are magmatic rocks of extreme commercial importance due to their resistance to coatings and ornamentation. Also, it is the material of choice in monuments.

– Marble: metamorphic rock from limestone that is found in a multitude of colors and textures that make it very visually appealing for use in ornaments, statues and fine decorative coatings.

– Clay: collected from sedimentary rocks is extremely malleable and is therefore used in the manufacture of bricks, floors and coatings, as well as various types of utensils ornamental.

– Limestone: sedimentary rock with one of the most versatile minerals for use in cement, lime, stone crushed, as well as in the metallurgical, chemical, paint industry and as acidity corrector of floors.

– Basalt: magmatic rock widely used in civil construction in the form of crushed stone and aggregate in mixtures of asphalt, mortar and concrete.

Energy sources

Originated in the process of weathering of sedimentary rocks over the centuries, or more well millennia, where the slow decomposition of organic matter creates what we call fuels fossils. Despite being a non-renewable energy source, they are the most used since the first industrial revolution to the present, being responsible for more than 80% of the energy generated in 2019. The main fuels are coal, natural gas and oil.

– Mineral coal: used mainly for power generation in thermoelectric plants.

– Natural gas: extremely versatile, it is capable of replacing other energy sources for use in thermoelectric plants, as well as almost all petroleum derivatives in the combustion of fuels for automobiles (with the exception of diesel in airplanes), as a raw material in the petrochemical industry in the production of solvents and fertilizers.

– Oil: considered the most important source today, it is used mainly as automotive fuel such as diesel and gasoline. Its derivatives are transformed into paints, solvents, detergents, plastics, rubber, explosives, among many other applications.

Extraction of minerals and metals

– SALT: obtained through the process of extracting rocks or evaporating seawater. It is essential in the kitchen and for our body.

– Metallic deposits: they are the metals obtained exclusively from the extraction of rocks, that is, they are products of their formation process. Among them we highlight diamond (crystal), gold, silver, lead, tin, copper, aluminum, zinc, manganese and calcium. Its uses are as varied as possible, from ornamentation, the chemical industry, electrical conductors, insulation, electrical and electronic components, etc.

– Nitrate, phosphate and potassium: They are used as preservatives, fertilizers in medicines and in the chemical industry of herbicides, detergents and explosives.

Agriculture

Rocks play an important role in the formation of soils suitable for agriculture. However, the technology and knowledge we have today allow us to simulate the natural mineralization of the soil to ensure better agricultural performance.

Phosphorus is one of the essential nutrients for plants and agricultural crops consume almost 90% of the extracted phosphorus, which guarantees a higher yield.

The use of rock (rock dust) reduces acidity and increases soil fertility. A sustainable alternative to chemical fertilizers that has been gaining ground in current agriculture and environmental meetings as a good option to reduce production costs while allowing the correction of the soil and consequently an improvement of the productivity.

Tourism

Tourism, as we already know, involves the local economy and is very important for families in that region, as well as being a visual gift that nature gives us. There are various rock formations around the world that attract tourists from all over the world.

As famous examples we cite:

– Grand Canyon, a natural formation of red rock layers located in the United States.

– The Giant's Causeway in Northern Ireland is a rock formation resulting from a volcanic eruption made up of several interconnected basalt columns.

– Wave Rock is a wave-shaped rock located in Australia. The shape naturally obtained over the years by the erosion of the lower part, together with the striped coloration washed down by the rains, give it a unique appearance.

– Perito Moreno is one of the most famous glaciers in the world. Yes, glaciers are also rocks. Formed by the metamorphism of thousands of snowflakes, this beautiful landscape is located in the Argentine Patagonia.

Despite not being the focus of this article, it is important to highlight that the different uses of rocks have an environmental cost. growing and that the search for more ecological substitutes is in constant discussion among the main potentials and studies for their development.

study and history

Petrology, a branch of geology that is dedicated exclusively to the study of rocks, is of the utmost importance since the earth's crust is basically made up of rocks.

The history of the planet earth is embedded in the rocks, either through fossils or through the change in the composition of the rocks, and with this we can evaluate the influence of climatic conditions about him environment and the organisms that lived there. Understanding the complex remodeling to which the planet has been constantly undergoing since its most remote times allows glimpse the evolution of man and nature up to the present moment and the path we are following towards the future.

Another important aspect to know the rocks more deeply is our dependence on the natural resources that we obtain from them to maintain our lifestyle. As has already been said, from the rocks we extract various minerals, fuels, water and the bad planning of these resources can affect the lives of millions of people.

It is also with this knowledge that we can try to predict the action of nature, such as volcanic eruptions and movements of tectonic plates, and with that to evaluate the potential risks that allow planning measures anticipated. But it is not only the action of nature that generates potential risks, the action of man affects the sedimentation and erosion processes and consequently in the environment, which affects the community in its set.

References

– Rocks and Minerals – NPS

– What are sedimentary rocks? – USGS

– Sedimentary Rocks – National Geographic

– World Energy Outlook 2021

– Fossil fuel – Britannica