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If a rock has large crystals, it is an intrusive rock. Intrusive rocks form underneath the Earth's surface. Magma cools slowly so it has time to form large crystals. An example is granite, where you can see the crystals with your naked eye. Rocks that have small crystals are extrusive rocks. Extrusive rocks are ones that form from lava (blasted out of a volcano) so they cool very quickly, not allowing large crystals to form. An example is obsidian, where you cannot visibly see the small crystals; it just looks like one black, glassy rock.

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What type of rock can be extrusive or intrusive?

Igneous rocks can be either extrusive or intrusive. Extrusive igneous rocks form from lava cooling quickly on or near the Earth's surface, resulting in small crystals. Intrusive igneous rocks form from magma cooling slowly beneath the Earth's surface, resulting in larger crystals.


How does the rate of cooling influence crystal size of igneous rocks and how does that help you to distinguish between intrusive and extrusive igneous rocks?

The longer that magma is able to cool, the larger the crystals will be. Intrusive rocks will have larger crystals than extrusive rocks. For example granite (intrusive) has larger grains than rhyolite (extrusive).


Which igneous rock can be intrusive and extrusive?

A porphyritic igneous rock demonstrates some extrusive characteristics and some intrusive characteristics. The appearance of phenocrysts (larger crystals) in a fine matrix (small crystals) indicates that the magma had time to cool slowly enough underground to form larger crystals before being erupted at or near the surface.


What igneous rocks are both intrusive and extrusive?

The igneous rocks that can be both intrusive and extrusive are known as porphyritic rocks. These rocks form when magma partially cools underground (intrusive) before being erupted onto the Earth's surface where the remaining magma cools quickly (extrusive). This dual cooling process creates distinctive textures in the rock, with larger crystals (phenocrysts) embedded in a finer-grained matrix.


True or false intrusive igneous rock forms small crystals because it cools rapidly?

True. Intrusive igneous rock, also known as plutonic rock, forms larger crystals because it cools slowly underground. Extrusive igneous rocks cool rapidly on the Earth's surface, forming smaller crystals.

Related Questions

What type of rock can be extrusive or intrusive?

Igneous rocks can be either extrusive or intrusive. Extrusive igneous rocks form from lava cooling quickly on or near the Earth's surface, resulting in small crystals. Intrusive igneous rocks form from magma cooling slowly beneath the Earth's surface, resulting in larger crystals.


How does the rate of cooling influence crystal size of igneous rocks and how does that help you to distinguish between intrusive and extrusive igneous rocks?

The longer that magma is able to cool, the larger the crystals will be. Intrusive rocks will have larger crystals than extrusive rocks. For example granite (intrusive) has larger grains than rhyolite (extrusive).


Which igneous rock can be intrusive and extrusive?

A porphyritic igneous rock demonstrates some extrusive characteristics and some intrusive characteristics. The appearance of phenocrysts (larger crystals) in a fine matrix (small crystals) indicates that the magma had time to cool slowly enough underground to form larger crystals before being erupted at or near the surface.


Is an intrusive crystal bigger than an extrusive crystal?

Typically, intrusive crystals are larger than extrusive crystals because intrusive rocks cool slowly beneath the Earth's surface, allowing larger crystals to form, while extrusive rocks cool quickly at the surface, producing smaller crystals.


When a igneous rock with large cystals cools what is it?

An intrusive igneous rock has larger crystals than an extrusive igneous rock because it has had a longer period of time to solidify underground.


Does extrusive or intrusive igneous rock form when lava cools quickly?

Extrusive igneous rock forms when lava cools quickly on the Earth's surface. This rapid cooling prevents large crystals from forming, resulting in a finer-grained texture. In contrast, intrusive igneous rock forms when magma cools slowly beneath the surface, allowing for the development of larger crystals.


What igneous rocks are both intrusive and extrusive?

The igneous rocks that can be both intrusive and extrusive are known as porphyritic rocks. These rocks form when magma partially cools underground (intrusive) before being erupted onto the Earth's surface where the remaining magma cools quickly (extrusive). This dual cooling process creates distinctive textures in the rock, with larger crystals (phenocrysts) embedded in a finer-grained matrix.


True or false intrusive igneous rock forms small crystals because it cools rapidly?

True. Intrusive igneous rock, also known as plutonic rock, forms larger crystals because it cools slowly underground. Extrusive igneous rocks cool rapidly on the Earth's surface, forming smaller crystals.


What is the name of igneous rocks that have large crystals and small crystals?

Large Crystals = Intrusive Small Crystals = Extrusive The name relates to where the minerals were cooled (at at what rate). In the case of intrusive igneous, the rocks were formed above Earth's surface and were thus cooled quickly and the minerals had little time to become defined. Extrusive rocks, therefore, were formed within the Earth's mantle and had a much longer time before being gathered to cool (as they slowly rose to the top).


What are the two different types of igneaous rock how do they look different?

The two main types of igneous rock are intrusive and extrusive. Intrusive rocks form underground and have larger crystals due to slower cooling. Extrusive rocks form on the Earth's surface and have smaller crystals due to rapid cooling.


What is the difference in appearance between igneous rocks that have cooled slowly and igneous rocks that have cooled quickly?

Igneous rocks that cooled slowly are intrusive. Igneous rocks that cooled quickly are extrusive. Intrusive rocks form larger crystals, because the crystals have a longer time to grow. Extrusive rocks have small to no crystals, because they had little or no time to grow/form.


What is the difference between a intrusive igneous rock ad an extrusive rock?

instrusive is inside the valcano and exstrusive comes onto earth's crust