Textures are of a rock are the size, grains, and the arrangements of grains in the case of sedimentary rocks or Crystal in the cases of metamorphic and igneous rocks. Textures are used by geologists in determining the mode of origin.
For igneous rocks there are six main types of textures, they include:
1. phaneritic
2. aphanitic
3. porphyritic
4. glassy
5. pyroclastic
6. pegmatitic
Intrusive Igneous rocks have the PHARNERITIC textures. These rocks crystallize slowly beneath the earth's surface. Examples may include granite and gabbro.
Volcanic rocks are also found below the earth's surface but differs from intrusive igneous rock by being of volcanic origin. The texture of volcanic rocks are APHANITIC to glassy texture. Examples are andesite and basalt.
Seismic waves are fundamentally of two types, compressional, longitudinal waves or shear, transverse waves. Through the body of the Earth these are called P-waves (for primary because they are fastest) and S-waves (for secondary since they are slower).
