Not all of them. Volcanic glass does not have crystals.
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.
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.
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.
Some rocks may contain crystals, but not all rocks contain crystals. Crystals can be found in rocks that have volcanic origin.
== Grain size. Most intrusive igneous rocks will have visible crystals. Crystals in most extrusive igneous rocks are not easily visible.
Yes. All intrusive igneours rocks and many extrusive rocks have crystals.
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.
Not necessarily. Intrusive igneous rocks, especially pegmatites, can have large crystals.
Igneous rocks will develop large crystals is they cool slowly underground.
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.
Igneous rocks with large crystals are known as intrusive or plutonic rocks. These rocks form underground as magma cools slowly, allowing large crystals to grow. Common examples include granite and diorite.
Crystals can form in all three types of rocks. Igneous rocks, like granite, form from the cooling and solidification of magma. Sedimentary rocks, such as limestone, can contain crystals that formed from precipitation of minerals in water. Metamorphic rocks, like marble, can have crystals that grew under extreme heat and pressure.