Basalt Fine Porphyritic

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Porphyritic Textures with Fine-Grained Groundmasses

This is a fine-grained basalt with olivine phenocrysts (pale green blobs). This is an andesite with amphibole (hornblende) phenocrysts. This is a porphyritic rhyolite. The photo below is a close up. The blocky gray and white crystals are feldspar (one K-spar, one plag), and the dark gray, almost

Porphyritic - Wikipedia

Porphyritic is an adjective used in geology, specifically for igneous rocks, for a rock that has a distinct difference in the size of the crystals, with at least one group of crystals obviously larger than another group. Porphyritic rocks may be aphanites or extrusive rock, with large crystals or phenocrysts floating in a fine-grained ...

Porphyritic Basalt - PiratePanel

Name: Porphyritic Basalt: Texture: Porphyritic: Origin: Extrusive/Volcanic: Chemical Composition: Mafic: Color: Dark Gray to Black: Mineral Composition: Calcium ...

Porphyritic basalt - Dunbar | Virtual Microscope

The basalt is Carboniferous in age with 1-2 mm sized plagioclase phenocrysts and a fine grained groundmass. The thin section shows that plagioclase phenocrysts are mostly altered to sericite, and groundmass contains altered grains of finer-grained plagioclase, altered biotite and altered glass.

What is a porphyritic igneous rock? - Quora

Porphyritic is an adjective used in geology specifically for describing igneous rocks and denotes rock textures typically found in volcanic rocks containing distinct crystals or crystalline particles embedded in a fine-grained groundmass. Most types of igneous rocks will display some degree of porphyritic texture.

Basalt - Igneous rocks

Basalt - an overview | ScienceDirect Topics

Tholeiitic basalt often represents a fine, glassy groundmass consisting of fine-grained quartz and other main constituent minerals. Tholeiitic basalt has fine-porphyritic texture, which is characterized by pyroxene/plagioclase phenocrysts ( Fig. 4.39 ) in fine glassy groundmass.

Porphyry - Igneous Rocks

Porphyritic texture is a very common texture in igneous rocks in which larger crystals (phenocrysts) are embedded in a fine-grained groundmass. Porphyry is an igneous rock that contains larger crystals (phenocrysts) in a fine-grained groundmass.

Basalt - Wikipedia

By definition, basalt is an aphanitic (fine-grained) igneous rock with generally 45–53% silica (SiO 2) and less than 10% feldspathoid by volume, and where at least 65% of …

Basalt: Igneous Rock - Pictures, Definition, Uses & More

What is Basalt? Basalt is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill.

What is a porphyritic igneous rock? - Quora

Porphyritic is an adjective used in geology specifically for describing igneous rocks and denotes rock textures typically found in volcanic rocks containing distinct crystals or crystalline particles embedded in a fine-grained groundmass. Most types of igneous rocks will display some degree of porphyritic texture.

Basalt vs Andesite - rocksparenature

Basalt is a common extrusive igneous rock formed by the rapid cooling of basaltic lava exposed at or very near the surface of Earth Andesite is a dark, fine-grained, brown or greyish intermediate volcanic rock which is a commonly found in lava

Phenocryst & Porphyritic Textures | Science Trends

A phenocryst is visible large crystal embedded within a fine-grained matrix of smaller crystals. This combination of matrix and phenocrysts forms a porphyritic rock texture. This combination of matrix and phenocrysts forms a porphyritic rock texture.

basalt | Definition, Properties, & Facts | Britannica

Basalt, extrusive igneous (volcanic) rock that is low in silica content, dark in colour, and comparatively rich in iron and magnesium. Some basalts are quite glassy (tachylytes), and many are very fine …

Basalt ~ Learning Geology

Basalt is a fine grained volcanic igneous rock formed of plagioclase and pyroxene minerals. It is most commonly formed by lava flow and in sills and dykes . Basalt is similar to gabbro in composition but the difference lies in the grain size of the two rocks.

Basalt - an overview | ScienceDirect Topics

Tholeiitic basalt often represents a fine, glassy groundmass consisting of fine-grained quartz and other main constituent minerals. Tholeiitic basalt has fine-porphyritic texture, which is characterized by pyroxene/plagioclase phenocrysts ( Fig. 4.39 ) in fine glassy groundmass.

Types of Porphyritic Rocks - Mineral Processing & Metallurgy

Porphyry. — This name refers to the structure, which is formed of larger crystals set in a fine-grained or glassy ground-mass. The porphyritic structure may be plainly visible, the larger crystals being easily seen (phenocrysts), or it may require the microscope to bring it out.

Basalt Textures - Michigan Technological University

Porphyrite or porphyritic basalt is characterized by obvious crystals, usually of plagioclase, which is often white or tan in color. These crystals are typically interpreted as phases that formed before eruption, where magma was being stored (a “Magma Chamber).

Porphyritic - Wikipedia

Porphyritic is an adjective used in geology, specifically for igneous rocks, for a rock that has a distinct difference in the size of the crystals, with at least one group of crystals obviously larger than another group. Porphyritic rocks may be aphanites or extrusive rock, with large crystals or phenocrysts floating in a fine-grained ...

Igneous Rock Textures - Indiana University Bloomington

c) porphyritic texture (mixed fine and coarse) A hand specimen of a volcanic rock with porphyritic texture. Larger crystals of plagioclase feldspar (white), are suspended in a groundmass/matrix of fine grained dark and light minerals (thus the gray color).

Igneous Rock Textures - Indiana University Bloomington

c) porphyritic texture (mixed fine and coarse) A hand specimen of a volcanic rock with porphyritic texture. Larger crystals of plagioclase feldspar (white), are suspended in a groundmass/matrix of fine grained dark and light minerals (thus the gray color).

Basalt Porphyry “Flowerstone” | Fred Haynes

I found the rock variously labeled as porphyritic gabbro and basalt porphyry. OK, which is most appropriate? Is this best classified as an extrusive or intrusive rock? The groundmass is quite fine grained, but one can see other crystals besides the flowery feldspars.

Basalt - Homestead

Basalt is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or gray. The most common uses for this rock are as aggregate in highway construction, railroad ballast, and tile. Basalt is ...

Vesicular and Amygdaloidal Textures - University of Pittsburgh

This hand sample of vesicular basalt has olivine phenocrysts. Like the sample at the top, this one is vesicular, fine-grained, and porphyritic. A close-up appears below. Like the sample at the top, this one is vesicular, fine-grained, and porphyritic.

Mafic volcanic rocks - University of British Columbia

Thin Section Description: Texture: Porphyritic. The groundmass has domains of intersertal texture (glass occupies the wedge-shaped interstices between Plag laths), intergranular texture (the spaces between Plag laths are occupied by one or more grains of Px) and ophitic texture.

ALEX STREKEISEN-Basalt-

A basalt is a fine-grained basic igneous rock containing essential calcic plagioclase feldspar and pyroxene (usually Augite), with or without olivine. Basalts can also contain quartz, hornblende, biotite, hypersthene (an orthopyroxene) and feldspathoids. Basalts are often porphyritic and can contain mantle xenoliths. As basic rocks they contain between 45-50% silica, abundant Fe, Mg and Ca ...

Olivine Basalt Porphyry - Microscope

Olivine Basalt Porphyry Porphyry is a term that refers to the texture of a rock, rather than its chemical or mineralogical composition. Indeed, porphyries are generally defined as igneous rocks that feature large, prominent crystals embedded in a finer groundmass matrix.

Andesite - an overview | ScienceDirect Topics

Tholeiitic basalt often represents a fine, glassy groundmass consisting of fine-grained quartz and other main constituent minerals. Tholeiitic basalt has fine-porphyritic texture, which is characterized by pyroxene/plagioclase phenocrysts ( Fig. 4.39 ) in fine glassy groundmass.

Basalt Picture Gallery - ThoughtCo

Basalt is the most common volcanic rock, constituting nearly all of the oceanic crust and covering parts of the continents. This gallery presents some of basalt's variety, on land and in the ocean.

Igneous Rock Porphyritic Basalt | Q?rius

Scientists call these specimens, which resemble a chocolate-chip cookie, porphyritic rocks, and the larger crystals are called phenocrysts. The phenocrysts had started to form within the magma before it later cooled rapidly, probably due to that magma erupting at a volcano.