Aphanite
Aphanite, or aphanitic as an adjective, is a name given to certain igneous rocks that are so fine-grained that their component mineral crystals are not detectable by the unaided eye. This geological texture results from rapid cooling in volcanic or hypabyssal environments. As a rule, the texture of these rocks is not the same as that of volcanic glass, with volcanic glass being non-crystalline, and having a glass-like appearance.
Aphanites are commonly porphyritic, having large crystals embedded in the fine groundmass or matrix. The large inclusions are called phenocrysts.
They consist essentially of very fine-grained minerals, such as plagioclase feldspar, with hornblende or augite, and may contain also biotite, quartz, and orthoclase.Common rocks that can be aphanitic
