Hello how are you friends welcome back to your active geology channel for those who do not know me I am the engineer Luis Montilva and after a while without uploading videos I bring you this one in which I am going to talk about the types of rocks without further ado what to say let's start the earth's surface is made up of different materials among them we have the soil and the rocks today in this video we are going to focus specifically on the rocks a rock can be defined as a solid that is generated or formed naturally and that it is made up of an association of minerals depending on the association of minerals found in the rocks will have a different composition and therefore a different origin the geologist studies the association of these minerals in order to classify the rocks that give them I will explain below but first you must know everything about minerals if you still have any questions up here on the cards I leave you a video where he talked about the classification of rock-forming minerals well now if we continue with the classification of rocks there are many classifications depending on various authors, but the most general and well-known divides rocks into three different types: first, igneous rocks or also known as magmatic rocks, second, sedimentary rocks, and finally, metamorphic rocks, the first type of rock that I am going to talk about is igneous rocks, these are also known as magmatic rocks since they come from magma, they should know that magma is a fluid formed by molten rock found inside the earth which tends to rise towards the surface, even reaching the expulsion this happens when volcanoes erupt when the magma reaches areas of the earth's surface it begins to cool and therefore crystallize and solidify thus generating magmatic rocks that depending on whether the cooling is slow or fast of the magma and the area in that solidify can be subclassified into igneous rocks of two groups: plutonic and volcanic igneous rocks, plutonic or intrusive, originate when magma cools slowly and at a great depth within the earth's crust. These rocks are characterized by having large minerals that can observed with the naked eye or with the help of a magnifying glass the main plutonic rocks are granite, which is an igneous rock of different colors, it can have a gray, white or pink color depending on the minerals that compose it, including quartz, feldspars and micas Then we have the gabbro, it is a dark rock since its composition is mainly of ferro-magnesian minerals that are difficult to distinguish with the naked eye. This type of rock is generated mainly in the oceanic ridges. Then we have the other type of igneous rock, which are the volcanic igneous rocks or also known as extrusive rocks, these rocks are those that have been expelled or thrown to the earth's surface by the eruption of active volcanoes. In this case, the cooling of the magma occurs very quickly, which does not give time for the Therefore, mineral crystals grow in this type of rock. The minerals cannot be observed with the naked eye. If you want to know the mineral composition of these rocks, you must use a petrographic microscope. The main types of extrusive or volcanic rock are rhyolite, which is The extrusive example of granite is a rock that is gray to pink in color and with a mineral composition of quartz feldspars and micas. Basalt is the extrusive example of gabbro. It is a rock that has a dark color and is generated mainly at oceanic ridges. The pumice or Well known as pumice stone, it is a light-colored extrusive igneous rock that is full of many holes which are formed by the amount of gases that the magma possessed at the time of the eruption. Obsidian is a rock that is mainly shiny black in color, although it can becoming brown and even transparent does not have a crystalline structure this is the most basic of igneous rocks if you want to know a little more about these rocks and their classification I leave you a video in which I speak exclusively about igneous rocks here on the cards for if you want to go see it The second type of rocks that I am going to talk about are sedimentary rocks. These rocks are formed by the accumulation of sediments that come from weathering and weathering, erosion, transport and consolidation of sediments from any other type of rock that is It is found on the earth's surface, the accumulation of these rocks occurs mainly in layers that in geology we know as sedimentary strata, sedimentary rocks are mainly classified into two types, the first of which is known as detrital rocks and there are also chemical sedimentary rocks. detrital rocks are formed by the accumulation of sediments that, as I already told you, come from the erosion of rocks exposed to the surface, are generated by a cycle that we call the sedimentary cycle of which I also have a video that I leave up here on the cards The main detrital sedimentary rocks according to their grain size are shales, they are very very fine-grained sedimentary rocks composed mainly of silts and clays, they have a laminar structure, then there are sandstones with a slightly larger grain size, and the sediments can be distinguished. to the naked eye and are composed mainly of quartz and smaller amounts of feldspar and clay. Finally, the detrital sedimentary rocks with coarser grains are known as conglomerates or breccias, which are characterized by having large grains embedded in a matrix of sediments of medium size. much less the other type of sedimentary rocks are the sedimentary rocks of chemical origin which originate from the precipitation of dissolved minerals that are transported and concentrated in a basin that allows their accumulation the main sedimentary rocks of chemical origin are limestone which is a rock formed mainly by precipitates of very fine grains of calcium carbonate or calcite generally contain fossils of aquatic organisms other types of chemical sedimentary rocks can be rock salt or known as halite and also gypsum if you want to expand your knowledge about sedimentary rocks I also leave you a video in which he spoke specifically about this type of rock and its classification up here on the cards. The last but not least important group of rocks are metamorphic rocks, which are generated by being subjected to high pressures and temperatures of any kind. type of rock when changing the conditions of the environment in which the rocks are found, they stop being stable and begin to transform in order to adapt to the new conditions of pressure and temperature. This is what geologists know as metamorphism depending on the external appearance of these rocks. They can be classified into two main types: the first are laminar metamorphic rocks, which are generated by the mineral composition, which are mainly micas, which, being lamellar-shaped minerals, generate layer species with planes of weakness that can easily separate and break metamorphic rocks. The best-known laminars are slate, which is the one with the lowest degree of metamorphism, this rock is separated into thin sheets, they are of variable colors but mainly black, they have a shiny surface due to the presence of mica crystals, then we have the schist, which has a degree of greater metabolism can be observed with a great brilliance due to the greater growth of mica crystals in this case the sheets can be deformed and minerals such as garnet, andalusite, kyanite and staurolite are obtained and finally gneiss is a rock found banded where the dark ferro-magnesian minerals are separated from the light minerals such as quartz and feldspar this type of rock is the one with the highest degree of metamorphism the second group of metamorphic rocks are those known as crystalline these rocks do not have sheets and They are characterized by breaking irregularly without separating into sheets. They are generally homogeneous and made up of few minerals. The best-known crystalline metamorphic rocks are, first of all, marble that comes from the metamorphism of carbonate rocks such as limestone and dolomite. They can present various colors and even veins of different shades finally the quartzite that comes mainly from the metabolism of quartz sas sandstones its main component mineral is quartz has different colors ranging from white to pink and is a very hard rock and resistant to weathering if you wish learn a little more about this type of rock up here in the video cards where he explained everything you need to know about metamorphism and metamorphic rocks so you can go see it if you liked this video don't forget to subscribe to the channel and hit the bell so that they activate the notifications and thus be aware of everything that I am publishing about geology that was all for today see you in the next episode of active geology