What are the possible textures of an igneous rock?

Answer 1

This question has a very complex answer and you would do best to look at a chart, in order to have a full grasp of the answer. There are several categories and subcategories, so the answer can vary, depending on the depth of the answer being sought and the setup of the chart you are using. Because of this fact, if you are learning this subject in school, and seeking to answer your teacher's / professor's question, then you might want to check your book for a chart first.

To answer your question though, the categories are as follows:

Phaneritic, which means it contains coarse grains / visible crystals. Within the phaneritic category, there is a subcategory which contains larger crystals, called pegmatitic, (but they are still phaneritic too).

Porphyritic, which means it contains a mixture of coarse and fine grains, to put it simply. (To put it less simply, it is fine-grained and contains appreciable phenocrysts.)

Aphanitic, which means it is fine-grained.

Glassy, which looks like glass. (Think of obsidian.)

Vesicular, which contains gas holes, made from gas bubbles. (Think of pumice.) But depending on the chart, this category may or may not fall under glassy, since pumice, for example is actually made of frothy glass. Futhermore, some types of vesicular rocks may be subdivided into a category called frothy.

Pyroclastic, which is made up of fragmented volcanic debris. (However, this category may be divided depending on fragment size. The subcategories are volcanic tuff, (which has fragments under 2 mm in size), and volcanic breccia, (which has fragments over 2 mm in size).

Again, the answers sought can depend on the depth of knowledge being sought. For example, if you are seeking this answer for a school assignment, your teacher or professor might only be seeking phaneritic, aphanitic, porphyritic, glassy, and pyroclastic. However, they may want to see the subcategories of pegmatitic, frothy, vesicular, volcanic tuff and volcanic breccia. The answers can be more in depth too, but I hope this is enough to help you. Again, I recommend looking at any handouts or your book, if you are a student, in order to ascertain just what depth of knowledge your teacher / professor expects you to have.

Answer 2

The five textures of rock are glassy, porphyritic, aphanitic, phaneritic, and pegmatic. Glassy texture is defined as having no nucleation and conchoidal fracture. An example of this is obsidian where the magma cools rapidly. Porphyritic texture is shown in igneous rocks that have two distinct crystals. Aphanetic, or fine-grained, texture means that the rock has crystals that are too small to see without a lens (<1mm). Aphanetic rocks are of volcanic origin and they include rhyolite, andesite, and basalt. On the other hand, phaneritic texture has visible crystals and is said to be coarse-grained. Pegmatic texture is very coarse grained. Though there are five common textures, one could also find vesicular texture in igneous rocks. It occurs when gas bubbles get trapped in cooling lava and become vesicles; rocks such as scoria, vesicular basalt, and pumice are included in this category. Another identifiable texture is pyroclastic (or fragmental), which includes volcanic tuff and volcanic breccias. The word pyroclast directly translates to fire broken; thus, pyroclastic rocks include volcanic ash fragments and volcanic bombs.

Answer 3

Igneous rock textures:

• phaneritic - larger visible crystals
• aphanitic - microscopic crystals
• porphyritic - combination of phaneritic and aphanitic
• glassy - no crystals
• vesicular - containing holes (usually from gas escaping)
• pegmatitic - extremely well-formed large crystalline texture

Answer 4

The texture of an igneous rock varies between the rock. Obsidian has a glassy and smooth texture, while pumice has a very rough and porous texture. There is no one texture that describes all igneous rocks.

Answer 5

The possible textures of an igneous rock include aphanitic (fine-grained), phaneritic (coarse-grained), porphyritic (mixed grain sizes), glassy (no visible grains), and vesicular (with holes formed by gas bubbles).

Answer 6

Granite, gabbro, and diorite are three that I can think of.

Answer 7

intutiv extrucive

Answer 8

nothing