* Phaneritic texture: Phaneritic rocks have large crystals that are visible to the naked eye. These rocks form when magma cools slowly underground, allowing the crystals to grow large.
* Aphanitic texture: Aphanitic rocks have small crystals that are not visible to the naked eye. These rocks form when magma cools quickly, preventing the crystals from growing large.
* Porphyritic texture: Porphyritic rocks have a combination of large and small crystals. The large crystals are called phenocrysts, and the small crystals are called groundmass. Porphyritic rocks form when magma cools in two stages: first, the magma cools quickly, forming the phenocrysts; then, the magma cools slowly, allowing the groundmass to form.
In addition to these three main categories, there are also a number of other igneous rock textures, such as:
* Glassy texture: Glassy rocks have no crystals. They form when magma cools so quickly that the atoms do not have time to form crystals.
* Vesicular texture: Vesicular rocks have small holes or vesicles. These holes are formed when gas bubbles are trapped in the magma as it cools.
* Amygdaloidal texture: Amygdaloidal rocks have small, almond-shaped cavities that are filled with minerals. These cavities are formed when gas bubbles are trapped in the magma and then filled with minerals as the magma cools.
Igneous rock textures can provide information about the conditions under which the rock formed. For example, phaneritic rocks indicate that the magma cooled slowly underground, while aphanitic rocks indicate that the magma cooled quickly. Porphyritic rocks indicate that the magma cooled in two stages, while glassy rocks indicate that the magma cooled very quickly.