'Phaneritic' refers to a texture found in some igneous and metamorphic rocks. Rocks with phaneritic texture are comprised of large crystals that are clearly visible to the naked eye.

This may seem arbitrary, but in many types of rock there is no smooth continuum of mineral crystal formation. Rocks that cool in the Earth's atmosphere (volcanic rocks) have little time to form crystals, so the resulting crystals are invisible without magnification. These rocks are said to have an aphanitic texture.

Rocks that cool underground in plutons (plutonic rocks) have time to form much larger crystals, generally half a millimeter to several centimeters in size. These crystals are nearly always large enough to be seen without magnification, although in dark rocks such as gabbro it may be hard to pick out the grains. The three most common phaneritic rocks are gabbro (formed from mafic magma), diorite (formed from intermediate magma), and granite (formed from felsic magma). These all have aphanitic counterparts; basalt, andesite, and rhyolite, respectively.

In phaneritic rocks the entire rock is formed from large grains. There is a third texture type, know as porphyritic, in which there is a fine-grained groundmass with larger crystals visible within the mass. It is easy to confuse porphyritic and phaneritic rocks, so look carefully!

In metamorphic rocks the distinction between textures is not so clearcut, and while the terms phaneritic and aphanitic are used, many other descriptive terms, such as foliation and gneissic texture, are also used. In the metamorphic rocks, larger crystals indicate greater pressure/temperatures.

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