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Porphyritic texture indicates that a magma has gone through a two stage cooling process. The magma has cooled sufficiently underground to allow some minerals to crystallize and grow in size; the magma is then expelled above ground where the remaining liquid magma solidifies quickly, allowing only small crystals to develop.
What else can I help you with?
What does phaneritic mean?
Phaneritic refers to igneous rock grain size,which is visible with the naked eye.
What determines the mineral grain size in an igneous rock?
The rate of cooling of the magma primarily determines the mineral grain size in an igneous rock. Rapid cooling results in fine-grained rocks, while slow cooling allows for the formation of coarse-grained rocks. Additionally, the composition of the magma and the presence of nucleation sites can also influence the final grain size.
How do you find the grain size in igneous rocks?
To determine the grain size in igneous rocks, you can use a microscope or a hand lens to examine the rock's mineral crystals. Measure the diameter of individual grains, typically in millimeters. Grain size is often classified as fine-grained (less than 1 mm), medium-grained (1-5 mm), or coarse-grained (greater than 5 mm). Additionally, you can use standard charts or scales to categorize the size and texture of the rock.
What is the grain size of a fine grained igneous rock?
The individual grains (crystals) in quickly cooled magma are described as aphanitic--not visible without magnification.
Which 2 groups is broken down into smaller groups by grain size?
Sedimentary rocks and igneous rocks can be broken down into smaller groups based on grain size. In sedimentary rocks, grain size categories include clay, silt, sand, and gravel. In igneous rocks, grain size categories include fine-grained, medium-grained, and coarse-grained.
What does phaneritic mean?
Phaneritic refers to igneous rock grain size,which is visible with the naked eye.
What controls the grain size of igneous rock?
The cooling rate of magma primarily controls the grain size of igneous rock. Faster cooling results in smaller grains, while slower cooling leads to larger grains. Other factors that can influence grain size include the composition of the magma and the amount of gas or water present during solidification.
What determines the mineral grain size in an igneous rock?
The rate of cooling of the magma primarily determines the mineral grain size in an igneous rock. Rapid cooling results in fine-grained rocks, while slow cooling allows for the formation of coarse-grained rocks. Additionally, the composition of the magma and the presence of nucleation sites can also influence the final grain size.
Does grain size mean anything when identifying igneous rocks?
yes, it does. when a grain size in an igneous rock is small, it means that it was probably an extrusive rock, meaning it formed on land. but if the grain size is big, it means that the rock most likely formed underground, or it was intrusive. try remembering it like this- the larger the crystals, the more time the rock had to form, and magma cools faster on land, not giving the rocks much time to form.
What is a factor that controls grain size in igneous rock?
It depends on if it is intrusive or extrusive. If it is an intrusive rock, it is formed when magma hardens under the earth and has a larger grain size. If it is an extrusive rock, it is formed when lava hardens on the earth's surface and has a smaller grain size.
How can you determine if a igneous rock has had an intrusive or extrusive origin?
== Grain size. Most intrusive igneous rocks will have visible crystals. Crystals in most extrusive igneous rocks are not easily visible.
What is the grain size of an extrusive igneous?
The grain size of an extrusive igneous rock is typically fine-grained to aphanitic, meaning the individual mineral grains are not visible to the naked eye. This rapid cooling at the Earth's surface prevents large crystals from forming, resulting in a fine texture.
What size of rock texture refers to igneous rock?
The size of the mineral crystals in an igneous rock determines the rock's texture.
Is conglomerate intrusive or extrusive?
Neither. Conglomerate is a sedimentary rock. Intrusive and extrusive are descriptive terms used to classify igneous rocks.
What is the grain size of a fine grained igneous rock?
The individual grains (crystals) in quickly cooled magma are described as aphanitic--not visible without magnification.
What does grain size tell you about the orgin and cooling time of an igneous rock?
The larger the crystals, the more time it had to cool because the crystals had more time to grow
How is basalt different from gabbro?
Basalt and gabbro are both igneous rocks, with major differences in grain size and where they form. Basalt has fine-grained crystals and forms from lava flows on the Earth's surface, while gabbro has coarse-grained crystals and forms from magma cooling beneath the Earth's surface.
