Rocks can be defined in a basic concept as the natural aggregates present in the earth in large masses. The rocks are formed by one or more minerals, in a rock there may be major minerals that is why these are classified, to generate This type of classification rocks are divided into three large groups according to their origin, these can be: Igneous rocks, Metamorphic rocks and sedimentary rocks.
Characteristics of the Rocks:
Rocks are detrital materials that are peculiar to the mantle and the crust, as well as other equivalent parts of other planetary bodies, the rocks are usually formed by several mineralogical species (composite rocks) and rocks constituted by a single mineral (monomineralic rocks) , the rocks tend to have a very hard structure although some may be very soft, such as clayey rocks or sands.
The composition of the rocks can be determined depending on the amount of minerals you have, a rock can be determined by essential minerals, a very common example is granite rock, which always has quartz in its structure, in addition to feldspar and mica also , on the other hand it is also established that some rocks have accessory minerals, these are named as they appear in small proportions in the rock or may even be absent, which is why the composition of the same, an example may be the granite, this rock may contain zircon and apatite in smaller proportion.
To classify rocks it is necessary to take criteria such as chemical composition, texture, permeability, among other aspects, although the most used criterion for their description is the origin of them, that is, the way in which the rocks were formed, we call this (rock cycles).
Classification of the types of Rocks.
There are three groups or types of rocks in which they can be divided according to their origin, the rocks can be classified into:
ROCKS IGNEAS:
These rocks are formed when the magma (molten rocks) is cooled, this happens quickly on the surface or slowly inside the earth's crust when there is volcanic activity. This causes large masses, which go through a cycle called " cycle of the rocks, we call these rocks plutonic rocks.
ROCKS METAMORPHIC
These rocks are formed from other rocks that produce, their formation is based on the action of pressures and temperatures that are generated in the earth, this allows a transformation to occur within the rock, we call this "metamorphism".
ROCKS SEDIMENTARY
These rocks are formed on the earth's surface when materials are deposited form layers or strata, these materials are known as detrital, because they are formed from pieces of other rocks, estastambien we can call sedimentary rocks and organic if are formed from precipitation of chemical compounds or accumulation of remains of living beings (fossils).
Types of Igneous Rocks:
Plutonic Rocks: These rocks are formed by slowly cooling the magma inside the crust, as the cooling of the magma is very slow, minerals have time to grow, so in these rocks you can see large crystals, this type The rock is very dense and does not have holes, the granites are the most common plutonic rocks, composed of quartz, feldspar and micas minerals.
Volcanic rocks :These rocks are formed when the magma is cooled on the surface at very low temperature and pressure, as there is a very rapid cooling the crystals do not have much time to form and grow, so in this type of rocks a constitution of masses of crystals of small size, or amorphous without cirstalization, these rocks have a spongy appearance, an example is basalt.
Filonianas Rocks: These rocks can crystallize in the interior of cracks or fractures produced in the rocks, product of the pressures, in these rocks the temperatures are not so high with the plutonic rocks, nor so low with the volcanic rocks.
Types of Metamorphism.
Metamorphism is classified according to the relative influence of pressure and temperature in the control of metamorphic rocks, endothermic reactions allow the formation of new minerals. The reaction rate increases with the increase in temperature, pressure and temperature increase in relation to the depth of the strata of the rocks, so that a process of metamorphism is originated, it is necessary that the rock receives a pressure of 2 kilobars.
Types of Sedimentary rocks.
DETRITICS: these rocks are formed from the sedimentation process, which is generated by the particles of the rocks that are transported by the wind. These rocks are classified according to the sizes of the particles that compose them.
CONGLOMERATES: rocks made up of large particles.
ARENISCAS: rocks constituted by grain particles of intermediate size.
LIMO AND CLAY: rocks that are made up of particles of very small sizes.
CHEMICAL AND ORGANIC ROCKS
These rocks are formed from the precipitation of certain chemical compounds in aqueous solutions or by accumulation of substances of organic origin, an example limestone rocks, formed by the remains of organisms, such as corals, algae and others, oil has its origin in this type of rocks that product of the accumulation of the rest of organic material this hydrocarbon is generated.
THE ROCKS ARE OF GREAT UTILITY FOR THE DAILY LIFE OF THE HUMAN BEING, SINCE PART OF ALL THE PRODUCTS THAT ARE OF OUR NEED ARE PRODUCED THROUGH THE VARIOUS ROCKS, FROM THE CREATION OF ENERGY TO THE UTILIZATION OF THE HYDROCARBON (PETROLEUM).
Bibliography :
- http://www.em.gov.bc.ca/MINING/GEOSCIENCE/PUBLICATIONSCATALOGUE/INFORMATIONCIRCULARS/IC1987-05/Pages/Classified.aspx
- http://csmgeo.csm.jmu.edu/geollab/Fichter/MetaRx/Metaclass.html
- https://en.wikipedia.org/wiki/List_of_rock_types
- https://geology.com/rocks/
- https://en.wikipedia.org/wiki/Rock_(geology)
- Roberts, Dar "Rocks and classifications " .Departement of Geography , University of California , Santa barbara , from original on 31 october 2013 .
- Wilson ,James Robert (2000) .A collectors guide to rock , mineral and fossil , Utah Geological survey . pp 1 -22 .