Is Obsidian Phaneritic or Aphanitic?

Examples of aphanitic igneous rock include basalt, andesite and rhyolite. Glassy or vitreous textures occur during some volcanic eruptions when the lava is quenched so rapidly that crystallization cannot occur. The result is a natural amorphous glass with few or no crystals. Examples include obsidian.Click to see full answer. Then, what is the difference between Aphanitic and Phaneritic?Rocks that are aphanitic have a grain size below 1 millimetre. On the other hand, phaneritic rocks have grains that are coarse and the grain size is usually between 1 millimetre and 10 millimetres.One may also ask, what is Aphanitic texture? Aphanitic – This texture describes very fine grained rock where individual crystals can be seen only with the aid of a microscope, i.e. the rock is mostly groundmass. An aphanitic texture is developed when magma is erupted at the Earth’s surface and cools too quickly for large crystals to grow. Considering this, is Obsidian intrusive or extrusive? Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. Obsidian is produced when felsic lava extruded from a volcano cools rapidly with minimal crystal growth.Do igneous rocks that cool slowly at depth display an Aphanitic or Phaneritic texture? Igneous Rock Textures Aphanitic (a = not, phaner = visible) rocks in contrast to phaneritic rocks, typically form from lava which crystallize rapidly on or near Earth’ surface. Because extrusive rocks make contact with the atmosphere they cool quickly, so the minerals do not have time to form large crystals.