Which of the following best describes an aphanitic texture? the rock is crystalline; mineral grains are too small to be visible without a magnifying lens or microscope.

What best describes an aphanitic igneous rock?

Which of the following best describes an aphanitic texture? The rock contains broken fragments and is volcanic in origin. The rock has mineral grains that are glassy. The rock is crystalline, but mineral grains are too small to be seen with the unaided eye.

What types of rock is Aphanitic texture?

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 and pumice.

How are aphanitic textures formed?

An aphanitic texture is developed when magma is erupted at the Earth's surface and cools too quickly for large crystals to grow. This texture is exhibited by some volcanic rocks.

Which of the following best describes a pegmatitic texture?

Which of the following best describes a pegmatitic texture? has a large percentage of voids and is lightweight, so therefore has the ability to float in water. ... Large crystals in pegmatites are the result of a high percentage of the melt being composed of water, carbon dioxide, and other materials.

Our Why... Evolving Textures Preview, TextureTalk Interview

Which of the following igneous rocks exhibit Aphanitic texture?

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.

Is a type of igneous rock with a felsic composition and an Aphanitic texture?

RHYOLITE - aphanitic (small crystals) of felsic minerals with the same composition of granite.

What is the meaning of Aphanitic texture?

Aphanitic texture consists of small crystals that cannot be seen by the eye with or hand lens. The entire rock is made up of small crystals, which are generally less than 1/2 mm in size. ... Igneous rocks are therefore classified as either intrusive (plutonic) or extrusive (volcanic).

What is texture describe the Inequigranular texture of igneous rock in detail?

Inequigranular texture

(i) Porphyritic texture : When an igneous rock contains large crystals some minerals set in a matrix which is much finer grained or even glassy, the texture is called “Porphyritic”. The large crystals are called “Phenocrysts” and fine grained material is called “groundmass”.

Which of the following is an aphanitic igneous rock quizlet?

Basalt is the aphanitic or fine-grained equivalent of gabbro. Plutonic rocks are intrusive and generally consist of mineral grains coarse enough to be readily visible in a hand sample. Glassy igneous rocks form when magma cools too fast for mineral grains to grow.

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. ... Basalt from surface lava flow often exhibits an aphanitic texture.

How do Aphanitic rocks differ from phaneritic rocks?

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

Are Aphanitic rocks intrusive?

Crystalline rocks with mineral grains that cannot be distinguished from one another without magnification have an aphanitic igneous texture. ... Intrusive igneous rocks thus have coarse-grained, or phaneritic, textures with visible crystals, and extrusive igneous rocks have fine-grained, or aphanitic, texture.

What is pyroclastic texture?

Pyroclastic texture results from the explosive fragmentation of volcanic material, including magma (commonly the light, frothy pumice variety and glass fragments called shards), country rock, and phenocrysts.

Where are pegmatite rocks found?

The hard rock minerals pegmatite and spodumene are found mainly in Australia. Read Lithium Mining Today May Influence What You Drive In the Future to learn more about lithium extraction and other potential sources of lithium.

What is the aphanitic or fine grained equivalent of gabbro?

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.

What determines the texture of an igneous rock?

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. ... In addition to texture, igneous rocks may are classified according to their chemical composition.

What is the texture of an igneous rock referring to quizlet?

Igneous rocks are classified by texture (the size of mineral grains and/or distribution of grain sizes) and composition (the types of minerals present). How are igneous rocks formed? Igneous rocks are formed by the cooling and solidification of magma, and are aggregates of predominantly silicate minerals.

What is the texture of intrusive igneous rock?

Intrusive rocks have a coarse grained texture. Extrusive Igneous Rocks: Extrusive, or volcanic, igneous rock is produced when magma exits and cools above (or very near) the Earth's surface. These are the rocks that form at erupting volcanoes and oozing fissures.

What is aphanitic?

Aphantic meaning

(geology) Of rock samples, compact, crystalline and too fine-grained in texture for its constituents to be identifiable.

What does the term aphanitic mean quizlet?

Aphanitic. Fine-grained, with crystals too small to identify without a microscope. Porphyritic. Consists of two or more different sizes of crystals; the large ones are phenocrysts and the small ones compose the groundmass or matrix.

How can we say that a rock is aphanitic?

Of or relating to an igneous rock in which the crystals are so fine that individual minerals cannot be distinguished with the naked eye. Aphanitic rocks are extrusive rocks that cooled so quickly that crystal growth was inhibited.

Is quartz an Aphanitic?

Aphanites are commonly porphyritic, having large crystals embedded in the fine groundmass, or matrix. ... They consist essentially of very small crystals of minerals such as plagioclase feldspar, with hornblende or augite, and may contain also biotite, quartz, and orthoclase.

What is the texture of gabbro rock?

Gabbro is mafic, intrusive, coarse-grained rock with allotriomorphic texture.