Social Sciences, asked by zencent, 7 months ago

cause anybody tell me about igneous rock in detail and also it's types..hhh..​

Answers

Answered by Anonymous
1

Explanation:

Igneous rock (derived from the Latin word ignis meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form natural glasses. Igneous rocks occur in a wide range of geological settings: shields, platforms, orogens, basins, large igneous provinces, extended crust and oceanic crust.

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Answered by anigavishal
1

Igneous rocks form when magma (molten rock) cools and crystallizes, either at volcanoes on the surface of the Earth or while the melted rock is still inside the crust. All magma develops underground, in the lower crust or upper mantle, because of the intense heat there.

Igneous rocks can have many different compositions, depending on the magma they cool from. They can also look different based on their cooling conditions. For example, two rocks from identical magma can become either rhyolite or granite, depending on whether they cool quickly or slowly.  

The two main categories of igneous rocks are extrusive and intrusive. Extrusive rocks are formed on the surface of the Earth from lava, which is magma that has emerged from underground. Intrusive rocks are formed from magma that cools and solidifies within the crust of the planet.

When lava comes out of a volcano and solidifies into extrusive igneous rock, also called volcanic, the rock cools very quickly. Crystals inside solid volcanic rocks are small because they do not have much time to form until the rock cools all the way, which stops the crystal growth. These fine-grained rocks are known as aphanitic—from a Greek word meaning “invisible.” They are given this name because the crystals that form within them are so small that they can be seen only with a microscope. If lava cools almost instantly, the rocks that form are glassy with no individual crystals, like obsidian. There are many other kinds of extrusive igneous rocks. For example, Pele’s hair is long, extremely thin strands of volcanic glass, while pahoehoe is smooth lava that forms shiny, rounded piles.  

Intrusive rocks, also called plutonic rocks, cool slowly without ever reaching the surface. They have large crystals that are usually visible without a microscope. This surface is known as a phaneritic texture. Perhaps the best-known phaneritic rock is granite. One extreme type of phaneritic rock is called pegmatite, found often in the U.S. state of Maine. Pegmatite can have a huge variety of crystal shapes and sizes, including some larger than a human hand.

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