what is the texture of an extrusive igneous rock

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Texture relates to how large the individual mineral grains are in the final, solid rock. Lavas that cool extremely rapidly may have a glassy texture. 4 Igneous Textures Elizabeth Johnson. Obsidian extrusive rock … Types of Magma Types of magma are determined by … Slow cooling usually causes this texture. Cooling rate and gas content create a variety of rock textures. These tiny crystals can be viewed under a petrographic microscope Sometimes lava is expelled violently in a volcanic eruption, or in other cases fissures open up in the Earth’s crust and … … A fine-grained texture is the product of rapid cooling and crystallization of lava. Rocks … Komatiite is a very rare and old extrusive igneous rock. The rocks here are basalts. Extrusive igneous rock, also known as volcanic rock, is formed by the cooling of molten magma on the earth's surface. Which describes a feature of extrusive igneous rocks after formation? When this liquid lava gets cooled, it solidifies and gets converted into igneous rocks. Progress % Practice Now. Igneous rocks are devided into intrusive and extrusive types. What is required to generate an igneous rock with a fine-grained texture? Igneous rocks can be distinguished by the composition of the magma and its texture. The inside of the Earth is very hot - hot enough to melt rocks. Generally, the longer the cooling time, the bigger the mineral crystals can grow. TUG … Identifying Igneous Rocks … produced from magma. A mineraloid is a form of volcanic glass that forms a smooth with consistent texture that fractures in a conchoidal manner. Extrusive rocks generally are smooth and glassy. Intrusive rocks have a coarse grained texture. 2. Molten (liquid) rock is called magma. … Mineral composition can only be identified with a microscope unless phenocrysts … These rocks include: andesite, basalt, dacite, obsidian, pumice, rhyolite, scoria, and tuff. Examples include granite, gabbro, diorite and dunite. Preview; Assign Practice; Preview. Because igneous rocks are formed from melted rock, which is in a thick viscous form, it can take on a wide variety of textures, appearances and compositions when it cools and solidifies. Igneous textures include the rock textures occurring in igneous rocks. The mineral grains are usually so small that they cannot be seen without the use of a hand lens or other magnifying device. Igneous rock has a coarse texture and is dark in color. Because of this, we assume that coarse grained igneous rocks are "intrusive," in that they … Such rocks are termed " extrusive" rocks. In general, the slower the cooling, the larger the crystals in the final rock. Extrusive Igneous Rocks: Extrusive, or volcanic, igneous rock is produced when magma exits and cools above (or very near) the Earth's surface. small crystals cooled quickly produced from magma formed at Earth's surface . It is the difference between intrusive and extrusive rocks that creates confusion in the minds of students. Practice. Most extrusive (volcanic) rocks have small crystals. As molten rock (called magma) below the surface cools, the liquid cloth starts to solidify into minerals of differing sizes and compositions. Within the igneous rock family, there are two different types: intrusive rocks (also called plutonic) which solidify from magma below the surface of the Earth, and extrusive rocks (also called volcanic) which erupt or solidify from lava above the Earth’s surface. Extrusive igneous rocks erupt onto the surface, where they cool quickly to form small crystals. These are the rocks that form at erupting volcanoes and oozing fissures. This means that they cool relatively quickly and under low pressures. Therefore, they are typically fine … Such rock is formed when the material solidifies at or near the surface so that the cooling is rather rapid. 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