Porphyritic textures are formed when large crystals are embedded in a matrix of small crystals.
If the crystals grow fast enough, they may form as part of the rock’s original texture while it is still molten.
Some igneous rocks with porphyritic texture include basalt, diorite andesite, obsidian, pumice and tuff.
The word “porphyritic” comes from the Greek words “poros,” meaning “pore” or “hole.”
Some examples of igneous rocks that have this type of texture include basalt, diorite andesite, obsidian, pumice and tuff.
There is also a form called spherulitic.