Based on Crystal Size:
* Phaneritic: Large crystals (visible to the naked eye), formed by slow cooling underground (intrusive). Examples: granite, gabbro.
* Aphanitic: Fine-grained crystals (too small to see without magnification), formed by rapid cooling on the surface (extrusive). Examples: basalt, rhyolite.
* Porphyritic: A mixture of large crystals (phenocrysts) embedded in a fine-grained matrix. This indicates a two-stage cooling process, with a slower initial phase followed by rapid cooling. Examples: porphyritic granite, porphyritic basalt.
* Pegmatitic: Very large crystals (often over a centimeter in size), formed by extremely slow cooling in the presence of water-rich fluids. Examples: pegmatite, aplite.
* Glassy: No crystals, formed by very rapid cooling (often in volcanic eruptions). Examples: obsidian, pumice.
Based on other characteristics:
* Vesicular: Contains numerous cavities (vesicles) formed by trapped gas bubbles during cooling. Examples: scoria, pumice.
* Amygdaloidal: Vesicles that have been filled with secondary minerals, such as zeolites or calcite. Examples: amygdaloidal basalt.
* Pyroclastic: Composed of fragments of volcanic rock and ash, often displaying a brecciated texture. Examples: tuff, agglomerate.
* Fragmental: Made up of angular or rounded fragments of other rocks, typically created by explosive volcanic eruptions. Examples: volcanic breccia, agglomerate.
* Equigranular: All crystals are approximately the same size.
* Inequigranular: Crystals are of different sizes.
Other Considerations:
* Texture can be used to identify the type of igneous rock. For example, granite is a phaneritic rock with quartz, feldspar, and mica crystals, while basalt is an aphanitic rock with plagioclase feldspar and pyroxene crystals.
* Texture also reflects the cooling history of the rock. A phaneritic texture suggests slow cooling, while an aphanitic texture suggests rapid cooling.
This list is not exhaustive, but it covers the most common igneous rock textures. Remember that igneous rocks can have a combination of textures, making them even more complex and interesting!
