The size of the crystals in an igneous rock tells us how fast the magma cooled.
If you're not looking for anything specific, any extrusive igneous rock will have smaller crystals, if any at all. This is because they cool quickly on the surface, leaving little time for crystals to form/grow.
Igneous rocks with big crystals or grains form from slow cooling beneath the Earth's surface, allowing time for larger crystals to grow. In contrast, igneous rocks with small crystals or grains form from fast cooling at or near the Earth's surface, limiting the time available for crystal growth.
Extrusive igneous rock consists of mineral crystals that are not observable with the naked eye. Obsidian is an extrusive igneous rock (volcanic glass) where there technically are no mineral crystals.
Igneous rocks will have small crystals if they cool rapidly. This is because rapid cooling does not allow enough time for large crystals to form. Examples of igneous rocks that exhibit small crystals due to rapid cooling include basalt and obsidian.
Igneous rocks can have both small and large crystals, depending on how quickly they cool. If an igneous rock cools slowly beneath the Earth's surface, it can form large crystals, while rapid cooling at the Earth's surface or in an eruption can result in small or no visible crystals.
Intrusive rock normally has visible crystals. Extrusive igneous rock has small crystals. A black extrusive igneous rock with small crystals could be basalt.
The size of the crystals in an igneous rock tells us how fast the magma cooled.
You would expect to find an igneous rock with small crystals near the Earth's surface where the rock cools relatively quickly, such as in volcanic eruptions or magma intrusions that do not have much time to grow large crystals. These rocks are known as volcanic or extrusive igneous rocks.
Andesite is an Igneous Rock. It has small crystals because it cooled quickly d;D
Igneous rocks with large crystals are called intrusive rocks, formed from magma cooling slowly beneath the Earth's surface, allowing for large crystals to form. Igneous rocks with small crystals are called extrusive rocks, formed from lava cooling quickly on the Earth's surface, resulting in small crystals due to rapid cooling.
Small
small crystals
The size of crystals in an igneous rock is called texture. Texture can range from fine-grained (small crystals) to coarse-grained (large crystals).
If you're not looking for anything specific, any extrusive igneous rock will have smaller crystals, if any at all. This is because they cool quickly on the surface, leaving little time for crystals to form/grow.
by the size of the crystals, big crystals intrusive, small crystals extrusive
The small crystals are formed outside the volcano by the cold air... the cold air cools down the igneous rock and the crystals dont have time to join together so the are small. And the big crystals are formed inside the volcano very slowly and that way they have time to join together then there are big crystals that have been formed.