What is the difference between Aphanitic and Phaneritic texture?

The main difference between Aphanitic and Phaneritic is that the aphanitic rocks are very finely grained and their crystals cannot be seen with the naked eye. While on the other hand, the Phaneritic rocks are large in size and can be easily seen from the naked eye.

How are phaneritic and aphanitic textures different?

APHANITIC TEXTURE – Igneous rocks that form on the earth’s surface have very fine-grained texture because the crystals are too small to see without magnification. PHANERITIC TEXTURE – Igneous rocks with large, visible crystals because the rock formed slowly in an underground magma chamber.

What makes a phaneritic rock different from aphanitic rock?

Phaneritic rocks cool slowly, and therefore have small crystals, while aphanitic rocks have large crystals and cool quickly. c. In phaneritic rocks, the crystals are large enough to be identified with the naked eye, while in aphanitic rocks they are not.

What does Aphanitic texture mean?

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.

What kind of texture does phaneritic have?

coarse-grained igneous texture

The texture of an igneous rock made up entirely of crystals big enough to be easily seen with the naked eye is phaneritic. Phaneritic texture is sometimes referred to as coarse-grained igneous texture. Granite, the most well known example of an intrusive igneous rock, has a phaneritic texture.

What does the term aphanitic mean?

Aphanitic is a descriptive term for small crystals, and phaneritic for larger ones. Very coarse crystals (those larger than 3 centimetres, or 1.2 inches) are termed pegmatitic. In igneous rock.

What is aphanitic and pyroclastic texture?

There are six main types of textures; phaneritic, aphanitic, porphyritic, glassy, pyroclastic and pegmatitic. Aphanitic (a = not, phaner = visible) rocks, in contrast to phaneritic rocks, typically form from lava which crystallize rapidly on or near Earth’s surface.

What is the meaning of phaneritic?

[ făn′ə-rĭt′ĭk ] Of or relating to an igneous rock in which the crystals are so coarse that individual minerals can be distinguished with the naked eye. Phaneritic rocks are intrusive rocks that cooled slowly enough to allow significant crystal growth. Compare aphanitic.

What is the difference between phaneritic and porphyritic rocks?

Phaneritic: any coarse-grained igneous rock, often intrusive, usually formed as a result of a longer cooling history (ex. granite, gabbro). Porphyritic: an igneous rock with one mineral (called the phenocryst) exhibiting a grain size larger than the remainder of the minerals (called the groundmass).

Is gabbro a phaneritic?

Gabbro (/ˈɡæb. roʊ/) is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth’s surface.

What does it mean if an igneous rock has an Aphanitic texture?

Aphanitic rock is igneous rock in which the grain or crystalline structure is too fine to be seen by the unaided eye. Such rock is formed when the material solidifies at or near the surface so that the cooling is rather rapid. Such rocks are termed “extrusive” rocks.

Is obsidian aphanitic or Phaneritic?

Classification of Igneous Rocks

What is the aphanitic equivalent of gabbro?

Basalt

Basalt is the aphanitic (fine-textured) extrusive equivalent of gabbro. From the Latin word “pumex”, meaning “pumice”. A vesicular, glassy volcanic rock, generally of rhyolite composition (felsic). Often light in color.

Which of the following igneous rocks exhibit Aphanitic texture quizlet?

Basalt is the aphanitic or fine-grained equivalent of gabbro.

Is olivine a phaneritic?

Colour – generally dark greenish-grey. Texture – phaneritic (coarse grained). Mineral content – generally olivine with lesser pyroxene ( augite) (dunite is dominantly olivine), always contains some metallic minerals, e.g. chromite, magnetite. Silica (SiO ₂) content – < 45%.

What is the phaneritic equivalent of basalt?

Gabbro. One example of a phaneritic rock with mafic composition; the coarse-grained equivalent of basalt.

Is aphanitic intrusive or extrusive?

Intrusive igneous rocks thus have coarse-grained, or phaneritic, textures with visible crystals, and extrusive igneous rocks have fine-grained, or aphanitic, texture.

What texture does basalt have?

Basalts show, almost always, aphanitic or fine-grained mineral texture resulting from rapid cooling of volcanic magma on or close to surface of Earth.

Where do igneous rocks with a coarse grained Phaneritic texture form?

Where do igneous rocks with a coarse-grained (phaneritic) texture form? Coarse-grained igneous rocks have large mineral crystals that are visible to the unaided eye because they formed deep under the surface of Earth where they were insulated by the surrounding rock and thus cooled and crystallized slowly.

What is the difference between coarse-grained and fine grained texture?

Coarse-grained rocks generally weather faster than fine-grained rocks. In fine-grained rocks, the particles are fine and packed closely together. … Coarse-grained rocks have particles which are more loosely packed and is more susceptible to weathering.

What is the difference between fine grained and coarse-grained igneous rock?

Coarse grain varieties (with mineral grains large enough to see without a magnifying glass) are called phaneritic. Granite and gabbro are examples of phaneritic igneous rocks. Fine grained rocks, where the individual grains are too small to see, are called aphanitic. Basalt is an example.

What are the different textures of igneous rocks?

There are nine main types of igneous rock textures: Phaneritic, vesicular, aphanitic, porphyritic, poikilitic, glassy, pyroclastic, equigranular, and spinifex. Each kind of texture has a variety of different characteristics that make them unique.

What determines texture of igneous rocks?

Extrusive or volcanic rocks crystallize from lava at the earth’s surface. The texture of an igneous rock (fine-grained vs coarse-grained) is dependent on the rate of cooling of the melt: slow cooling allows large crystals to form, fast cooling yields small crystals.