Rhyolite.
It depends on the type of igneous rock. Intrusive igneous rocks such as granite have large crystals, extrusive igneous rocks may have small crystals as in basalt or no crystals as in pumice.
The crystals in granite, being intrusive in nature, will be larger than those in basalt, an extrusive igneous rock. Intrusive igneous rocks have cooled slowly from magma, extrusive rocks have cooled quickly from magma. Crystals grow larger from slow cooling magma.
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).
Both are igneous rocks, formed from the cooling and solidification of magma. Granite is a felsic, intrusive igneous rock, with visible well mixed mineral crystals. Basalt is a mafic, extrusive igneous rock, composed of darker mineral crystals, most of which are not distinguishable without the aid of magnification.
A pegmatite is a rock formed under certain favorable circumstances that enhance the crystal size of the rock. The crystals would be larger than those in basalt, an extrusive igneous rock, and granite, and intrusive igneous rock.
granite
It depends on the type of igneous rock. Intrusive igneous rocks such as granite have large crystals, extrusive igneous rocks may have small crystals as in basalt or no crystals as in pumice.
Igneous rocks are usually classified by their chemical composition (acidic or basic), and by whether they formed underground (intrusive, characterised by large mineral crystals) or on the surface (extrusive, made of tiny, microscopic crystals). For instance, basalt is a basic, extrusive rock, and granite is an acidic, intrusive rock.
Porphyrite of any composition, granite, gabbro, diorite. Most intrusive igneous rocks have crystals large enough to see with the naked eye. Another term used to define an igneous rock with large crystals is coarse-grained.
The crystals in granite, being intrusive in nature, will be larger than those in basalt, an extrusive igneous rock. Intrusive igneous rocks have cooled slowly from magma, extrusive rocks have cooled quickly from magma. Crystals grow larger from slow cooling magma.
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).
Both are igneous rocks, formed from the cooling and solidification of magma. Granite is a felsic, intrusive igneous rock, with visible well mixed mineral crystals. Basalt is a mafic, extrusive igneous rock, composed of darker mineral crystals, most of which are not distinguishable without the aid of magnification.
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.
A pegmatite is a rock formed under certain favorable circumstances that enhance the crystal size of the rock. The crystals would be larger than those in basalt, an extrusive igneous rock, and granite, and intrusive igneous rock.
by the size of the crystals, big crystals intrusive, small crystals extrusive
Intrusive rock normally has visible crystals. Extrusive igneous rock has small crystals. A black extrusive igneous rock with small crystals could be basalt.
== Grain size. Most intrusive igneous rocks will have visible crystals. Crystals in most extrusive igneous rocks are not easily visible.