why are some igneous rocks coarse and others fine?
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The texture of an igneous rock (fine-grained vs coarse-grained) is dependent on the rate of cooling of the melt: slow cooling allows large crystals to form, fast cooling yields small crystals. ... They cool too quickly to form crystals.
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Igneous rocks form from molten rock, and rarely have fossils in them. Metamorphic rocks have been put under great pressure, heated, squashed or stretched, and fossils do not usually survive these extreme conditions. Generally it is only sedimentary rocks that contain fossils.
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Granite is a grainy, igneous rock that is composed of many different minerals. Marble has a softer look, due to its high concentration of calcite. Marble is mostly available in light white or pastel colors, although there are some darker slabs available. It's hard to find a color that granite does not come in.
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But granite rich in hornblende and dark mica is light gray with dark specks. Quartz crystals in granite add light gray or smoky specks. Many igneous rocks are hard, dense, and durable. People throughout history have used igneous rock for tools and building materials.
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Igneous rock, also known as volcanic rock, is formed by the cooling of magma or lava. This type of rock is classified by cooling time and the type of magma it is formed from. The properties of these rocks vary greatly, including their chemical composition, grain structure, texture and color.
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The texture of an igneous rock depends on the size of the crystals in the rock. This tells us if the rock is plutonic or volcanic. When magma cools underground, it cools very slowly and when lava cools above ground, it cools quickly. When magma and lava cool, mineral crystals start to form in the molten rock.
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Igneous rocks are formed by the cooling and solidification of magma or lava. Igneous rock is formed through the cooling and solidification of magma or lava. Igneous rock may formwith or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
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The Birth of a Mountain Range Igneous rocks are formed when molten rock solidifies. Igneous rocks can be plutonic or volcanic. Plutonic rocks, such as granite, form when magma cools slowly in the depths of the earth. Volcanic rocks, such as basalt, rhyolite, and andesite form when lava cools rapidly on the surface.
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Rocks are roughly divided into igneous, sedimentary, and metamorphic, and their ages is always less than 5 billion because they didn't come into being as early as earth did. For example, igneous is formed when magma cools down, but all magma didn't cool down when the earth came into being.
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Magmas that erupt as lava onto the earth's surface cool and solidify rapidly. Rapid cooling results in an aphanitic igneous texture, in which few or none of the individual minerals are big enough to see with the naked eye. This is sometimes referred to as a fine-grained igneous texture.
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Igneous rocks are rocks formed from the crystallization of a liquid (molten rock). Igneous rocks may be divided into two categories. Intrusive or plutonic rocks crystallize from magma beneath the earth's surface. Extrusive or volcanic rocks crystallize from lava at the earth's surface.
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Aphanitic, extrusive, igneous rocks therefore have coarse-grained, intrusive counterparts with the same chemical and mineral composition. For example, the silica-rich extrusive rock, rhyolite , common in continental volcanic regions, is the fine-grained equivalent of intrusive granite .
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Top 7 Differences Between Metamorphic Rocks and Igneous Rocks. Metamorphic rocks: arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". ... Igneous rock: is formed through the cooling and solidification of magma or lava.
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Igneous rocks are formed from lava or magma. Magma is molten rock that is underground and lava is molten rock that erupts out on the surface. The two main types of igneous rocks are plutonic rocks and volcanic rocks. ... When magma cools underground, it cools very slowly and when lava cools above ground, it cools quickly.
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There are two categories of igneous rocks. Volcanic rocks are rocks formed when lava cools and solidifies on the earth's surface. ... Plutonic rocks are rocks formed when magma cools and solidifies below the earth's surface.
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Igneous rocks are classified on the basis of texture and composition. Texture refers to the size, shape, and arrangement of the mineral grains or crystals of which the rock is composed.
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Igneous rocks formed when liquid magma or lava—magma that has emerged onto the surface of the Earth—cooled and hardened. A metamorphic rock, on the other hand, began as a rock—either a sedimentary, igneous, or even a different sort of metamorphic rock.