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When a magma cools down, it becomes a solid. Various atoms "prefer" to be arranged in a crystallic way. So when a magma cools down, crystals start to form and grow. Crystals only grow at their edges, so to make the crystal grow larger, it would need more time to do so. Magma's that cool slower have more time for the crystals inside them to grow, so the crystals will be larger, compared to a magma that cools quicker, or even a magma that comes out of the ground (then called a lava).
Wiki User
∙ 13y ago
Wiki User
∙ 13y agoI Think it is something to do with the fact that it interferes with the full crystal formation?
Wiki User
∙ 8y agosmall, because they did not have the time to grow any larger
Wiki User
∙ 10y agobecause the crystals have tim to grow
Wiki User
∙ 11y agoFaster cooling - smaller crystals.
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What does grain-size tell you about the cooling history of a rock?
Slower rates of cooling will create larger crystals. Rapid cooling allows little time for element accumulation in the crystal, therefore, the crystals created will be smaller. Larger, visible crystals in igneous rock indicate that the magma was slow cooling, usually at depth. Much smaller crystals in igneous rock indicate rapid cooling of lava, usually at or near the surface. Crystals in igneous rock will grow larger and have more time to accumulate material for their growth the more time they have at their crystallization temperature.
Why do plutonic rock and volcanic rock have big and small crystals respectively?
The size of the crystals is a function of the rate of cooling of the molten rock. The faster the molten rock cools, the smaller the crystals will be.
Why do some igneous rocks have larger crystals but other igneous rocks have crystals so small they have to be seen with a microscope?
Crystal size in igneous rock is dependent on the amount of time spent in cooling from magma or lava. More time means larger crystals. Rocks that have small crystals cooled quickly, so the minerals didn't have time to rearrange and form large crystals before the rock solidified. These small-crystalled rocks are described as aphanitic. Other rocks cooled slowly, so the minerals had time to rearrange and form large crystals before solidifying. These rocks are considered phaneritic. Some rocks cool slowly for a while, and then experience rapid cooling (such as magma that cools slowly inside a volcano, and then cools rapidly when the volcano erupts). Such rocks have large crystals surrounded by tiny crystals. Rocks that form this way are described as porphyritic.
What is slate's grain size?
Slaet in grain size is the size of sand crystals.
How are grains related to texture?
Grains in igneous rocks determine the rock's classification. They can be classified as:pegmatitic: very large crystalsphaneritic: rocks contain minerals with crystals visible to the unaided eye, commonly intrusiveaphanitic: rapid cooling, crystal nucleation and growth is stunted, forming a uniform, fine grained rockporphyritic: containing phenocrysts in a fine groundmassvesicular: contains voids caused by trapped gas while coolingvitreous: glassy or hyaline without crystalspyroclastic: rock contain fragments of crystals, phenocrysts and rock fragmentsequigranular: rock crystals are all the same size
How will cooling affect maple syrup crystal size?
Fast cooling=small crystals Slow cooling=big crystals
How does the speed of cooling of molten rock affect the size of crystals that form?
fast cooling rate forms smaller crystals eg Andesiteslow cooling rate forms large crystals eg.Pegmatite
What is the main factor that affects the size of minerals in igneous rocks?
Crystal size is largely dependent on the time the magma takes to cool and solidify. Slow cooling equals large crystals. Fast cooling equals small crystals.
What determines how large the crystals and an igneous rock Will be?
The speed at which the magma/lava cools ie. fast cooling = not much time for crystals to form = little or no small crystals slow cooling = much time for crystals to form = big crystals
As the rate of cooling of igneous rocks increases the size of the crystals that form?
The size of crystals decreases as the cooling increases. This is called an inverse relationship.
As the rate of cooling of igneous rocks increases the size of the crystals that form .?
The size of crystals decreases as the cooling increases. This is called an inverse relationship.
. As the rate of cooling of igneous rocks increases the size of the crystals that form?
The size of crystals decreases as the cooling increases. This is called an inverse relationship.
What determines crystal size in an igneous rock?
It depends on the cooling of lava. Slow cooling forms big crystals deep under the surface while fast cooling creates small crystals on or just below the earths surface. Itstant cooling wouls have no crystals.
Size of crystals made by slow cooling?
because the crystals gradually start to melt.
What effect does a fast cooling rate have on grain size in igenous rocks?
Fast cooling lava or magma creates an aphanitic or small crystal (grain) textured igneous rock.
What controls the grain size of igneous rock?
The rate at which the igneous rock cools controls grain size. Slower cooling results in larger crystals while faster cooling results in smaller crystals.
Explain pegmatite is coarse grained with large crystals basalt is fine grained with small crystals and obsidian has no crystals?
Crystal size in these rock types is determined by their rate of cooling. Pegmatites have large crystals due to very slow cooling. Obsidian has microscopic crystals due to almost instantaneous cooling.
