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Aphanites (adj. aphanitic; ) are that are so grain size that their component mineral are not visible to the naked eye (in contrast to , in which the crystals are visible to the unaided eye). This geological texture results from rapid cooling in volcanic rock or hypabyssal (shallow subsurface) environments. As a rule, the texture of these rocks is not the same as that of volcanic glass (e.g., obsidian), with volcanic glass being non-crystalline (amorphous), and having a glass-like appearance.
Aphanites are commonly porphyritic, having large crystals embedded in the fine groundmass, or matrix. The larger inclusions are called . They consist essentially of very small crystals of minerals such as plagioclase feldspar, with hornblende or augite, and may contain also biotite, quartz, and orthoclase.
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