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Larger crystal size is generally associated with longer cooling times, because large crystals take a long time to form. For this reason, intrusive (underground) igneous rocks have larger crystals than extrucive (above ground) rocks, due to the lack of insulation, and hence faster cooling, at the surface.
Wiki User
∙ 14y ago
Wiki User
∙ 12y agoCrystals need time to grow and magma cools much more slowly under the surface of the earth than when it erupts as lava. There are plenty of other things they need too, notably the chemical components within the magma itself - if you have lots of silicon, you get lots of quartz for instance.
Some crystals will only occur at deep depths where the pressure and heat is much higher, such as diamonds (you do not get diamonds from volcanic lava because of the lack of pressure and heat).
Wiki User
∙ 13y agoBecause of difference in their various modes of formations.
Wiki User
∙ 17y agoThey are older; more time to form.
Wiki User
∙ 13y agoNO. They also form on earths surface.
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Do rocks have crystals?
Some rocks may contain crystals, but not all rocks contain crystals. Crystals can be found in rocks that have volcanic origin.
Why do some rocks have crystal?
it all depends on the rate of cooling and crystallisation and the type of rock
Some WHAT igneous rocks have individual mineral crystals that are too small to be seen without magnification?
Some extrusive igneous rocks have individual mineral crystals that are too small to be seen without magnification.
What kind of rock formation is sometimes filled with crystals?
Geodes are rocks that are lined or filled with crystals. Pegmatites are rock formations that often exhibit extremely large crystals. Just a note--all rocks are composed of mineral crystals, with few exceptions. The crystals in some, however are just too small to see.
What is the relationship between cooling time igneous rocks and the size of its crystals?
Plutonic rocks are intrusive (they solidify before they reach the surface) and have larger crystals because the crystals have had a longer time to accumulate in the heat under the surface. Volcanic rocks are extrusive (they solidify on or near the surface) and have smaller crystals because the element has less time to accumulate when they cool quickly.
Why do some igneous rocks have bigger crystals then others?
some of them are formed inside the earth and take 100's of years to form and form large cyclists in that time
Why do some igneous rocks have big crystals or grains and some igneous rocks have small crystals or grains?
how long they stayed in the volcano; how much time the crystals had to form
Do rocks have crystals?
Some rocks may contain crystals, but not all rocks contain crystals. Crystals can be found in rocks that have volcanic origin.
What is th size grain of metamorphic rocks?
It varies some metamorphic rocks are fine grained (eg slate) and others have very large crystals (eg an augen gneiss).
Why do some rocks have crystal?
it all depends on the rate of cooling and crystallisation and the type of rock
Name some rocks which have crystals?
All rocks have crystals, or at least crystalline structures. Sedimentary rocks may not have crystals as such, but the individual grains have internal crystal structures. All magmatic and metamorphic rocks have crystals, though they may be too small to be seen without the aid of a microscope. Only possible exception is Obsidian (volcanic glass) which may be amorphous.
What type of rocks form due to cooling?
The earth is composed of various types of rocks, some formed as a result of pressure while others due to cooling. Igneous rocks form when molten lava cools and solidify to form crystals.
Are there crystal rocks by your home?
yes there are some rocks that are round called geodes these rocks are hollow on the inside and have crystals inside them
Why does igneous rock have bigger crystals and some have small crystals?
The reason why is because of where it comes from in a volcano and how fast it cools. If it cools slowly then it will have bigger crystals because the longer it has to cool the longer the crystals have to grow. So dose that answer your question
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.
Why is a igneous rock appear smooth and glassy?
Some igneous rocks are very smooth and glassy (obsidian) while others have a very rough texture, such as the rocks used on the bottom of a propane gas grill. They are all formed from lava, but the glassy rocks cooled so fast that crystals did not have a chance to form. The rougher rocks cooled more slowly, allowing larger crystals to form--Slower cooling = larger crystals = rougher texture.
Why do some igneous rocks have larger crystals than others?
The size of the crystals depend on the time it took the rock to cool. Slow cooling rocks have larger crystals because they had a longer time to grow their crystals. For example Basalt is an volcanic extrusive igneous rock that forms from rapid cooling of the magma and are usually located near the surface or on the ocean floor, it has finer crystals not visible by the naked eye. Granite is an intrusive igneous rock that forms from slow cooling of the magma within the earth crust, it has larger crystals.
