basalt fine porphyritic

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Basalt and Porphyry rocksparenature

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Mineral and Rock Guide booked City College of San Francisco

Add PORPHYRY to the name IF the rock displays porphyritic texture. If an aphanitic igneous rock has phenocrysts in it (large minerals surrounded by an aphanitic matrix), it is called porphyritic. Add the name of the prominent phenocryst mi neral to the front of the rock name. (Naming example olivine basalt

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basalt basalt Fine-grained or porphyritic igneous rock with less than 20 percent quartz, and less than 10 percent feldspathoid minerals, in which the ratio of plagioclase to total feldspar is greater 0.65. Typically composed of calcic plagioclase and clinopyroxene; phenocrysts typically include one or more of calcic plagioclase, clinopyroxene, orthopyroxene, and olivine.

BasaltGeology WikiFandom

Basalt has a fine-grained mineral texture due to the molten rock cooling too quickly for large mineral crystals to grow; it is often porphyritic, containing larger crystals (phenocrysts) formed prior to the extrusion that brought the magma to the surface, embedded in a finer-grained matrix.

Phsysical Geology, Igneous Rocks Union College

The dark-gray matrix was liquid at the time of eruption, but now has cooled and crystallized to fine-grained basalt. The minerals in the matrix are too small to identify, but the overall dark matrix color indicates that it is rich in mafic minerals. In igneous rocks, large crystals surrounded by a finer-grained matrix material are called

Igneous Textures Union College

Porphyritic texture in a trachite. Porphyries are rocks with a large fraction of phenocrysts, typically around 50%. At this phenocryst fraction, grain-on-grain contact would make them extremely viscous. Traditionally the phenocryst matrix in porphyries is relatively fine-grained, suggestive of extrusive rocks or shallow levels of intrusion

Mare Basalt Volcanism

A sequence of textural types within each basalt category represents different cooling histories. The textures range from vitrophyric to porphyritic to subophitic to intersertal to equigranular (see appendix I for definition of terms and/or appendix II for examples of texture). Most samples are fine-grained and have an average 16

Practice questions Igneous Rocks and Volcanoes

Igneous Rocks and Volcanoes Practice exam questions written by Timothy H. Heaton, Professor of Earth Sciences, University of South Dakota. Click the circle by an answer with the mouse, then click on the Submit button to get a response. You will be told if your answer is

what is porphyritic texture?Yahoo Answers

04.01.2021 · phenocrystscoarser-grained crystals set in a groundmass of fine-grained crystals or glass. If a rock has separate sizes of crystals, the coarse crystals are called . phenocrysts . A porphyritic rock with abundant, lath shaped plagioclases as phenocrysts is said to have intersertal texture . If a rock has a wide range of grain sizes that

WikiZero Mafic

Mafic is an adjective describing a silicate mineral or igneous rock that is rich in magnesium and iron, and is thus a portmanteau of magnesium and ferric. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite.Common mafic rocks include basalt, diabase and gabbro.Mafic rocks often also contain calcium-rich varieties of

Basalt rock ScienceDaily

Basalt is a common gray to black volcanic rock. It is usually fine-grained due to rapid cooling of lava on the Earth's surface. It may be porphyritic containing larger crystals in a fine matrix

Mafic Facts for Kids Kiddle

Mafic minerals are usually dark in color and have a specific gravity greater than 3. Common rock-forming mafic minerals include olivine, pyroxene, amphibole, biotite and other micas, augite and the calcium-rich plagioclase feldspars. Common mafic rocks include basalt and gabbro.

Basalt Chemeketa Community College

BASALT. Basalt is an extrusive igneous rock that is low in silica content, dark in color, and comparatively rich in iron and magnesium. Some basalts are quite glassy, and many are very fine-grained and compact; it is more usual, however, for them to exhibit porphyritic structure, with larger crystals (phenocrysts) of olivine, pyroxene, or feldspar in a finely crystalline matrix (groundmass

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Igneous rocks University of Auckland

Igneous rocks. Igneous rocks are formed by the solidification of magma, a silicate liquid generated by partial melting of the upper mantle or the lower crust.Different environments of formation, and the cooling rates associated with these, create very different textures and define the two major groupings within igneous rocks

Explain what aphanitic, phaneritic, and porphyritic mean

13.10.2021 · Porphyritic textures develop when conditions during cooling of a magma change relatively quickly. The earlier formed minerals will have formed slowly and remain as large crystals, whereas, sudden cooling causes the rapid crystallization of the remainder of the melt into a fine grained (aphanitic) matrix. The result is an aphanitic rock with

porphyritic Synonyms for porphyriticSynonyms Of

Porphyritic rocks may be aphanites or extrusive, with large crystals or phenocrysts floating in a fine-grained groundmass of non-visible crystals, as in a porphyritic basalt, or phanerites or intrusive, with individual crystals of the groundmass easily distinguished with the eye, but one group of crystals clearly much bigger than the rest, as

Porphyritic definition/meaning

Porphyritic rocks may be aphanites or extrusive, with large crystals or phenocrysts floating in a fine-grained groundmass of non-visible crystals, as in a porphyritic basalt, or phanerites or intrusive, with individual crystals of the groundmass may be easily distinguished with the eye, but one group of crystals clearly much bigger than the

American Educational Porphyritic Basalt Igneous Rock, 10

The American Educational 5009-03B porphyritic basalt igneous rock is used for geological study, and is a bulk specimen for hands-on learning. The 5009-03B consists of 10 rock pieces measuring 3.0 to 4.0cm (L) for detailed examination.

basalt Meteorite Identification

"Basalt is a common gray to black volcanic rock. It is usually fine-grained due to rapid cooling of lava on the Earth's surface. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or gray.

Basalt & andesite Refine Industrial Co.,LIMITED

Basalt is an extrusive igneous rock, sometimes porphyritic, and is often both fine-grained and dense. Basalt in the tops of subaerial lava flows and cinders will often be highly vesiculated, imparting a lightweight "frothy" texture to the rock.

70215 (306) Mare BasaltVirtual Microscope

70215 is a dense, fine-grained porphyritic mare basalt that has been used to create "touchstones" for public display. It was collected near the Lunar Module and is

Black Basalt and Detail Information world of stones

Flood basalt describes the formation in a series of lava basalt flows. Black Basalt and Detail Information. Black Basaltbasalt is an aphanitic (fine-grained) igneous rock with generally 45-55% silica (SiO 2) and less than 10% feldspathoid by volume, and where at least 65% of the rock is feldspar in the form of plagioclase. It is the most

7.3 Classification of Igneous RocksPhysical Geology

Exercise Which Mineral Will the Phenocryst Be? As a magma cools below 1300°C, minerals start to crystallize within it. If the magma is then erupted, the rest of the liquid will cool quickly to form a porphyritic texture. The rock will have some relatively large crystals (phenocrysts) of the minerals that crystallized early, and the rest will be very fine-grained or even glassy.

Mafic Simple English Wikipedia, the free encyclopedia

Mafic minerals are usually dark in color and have a specific gravity greater than 3. Common rock-forming mafic minerals include olivine, pyroxene, amphibole, biotite and other micas, augite and the calcium-rich plagioclase feldspars. Common mafic rocks include basalt and gabbro.

Igneous Rock Textures Indiana University Bloomington

A hand specimen of basalt with aphanitic (fine grained) texture. The dark color is due to abundant dark colored minerals (pyroxene, hornblende). C) PORPHYRITIC TEXTURE (MIXED FINE AND COARSE) A hand specimen of a volcanic rock with porphyritic texture.

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.

Where are basalt rocks found?AnswersDrive

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. It has a composition similar to gabbro.

Igneous Rock Textures ThoughtCo

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.

Buttress Dolerite (CTJb;0) USGS

Geologic unit mapped in Connecticut Dark-gray to greenish-gray (weathers brown or gray), medium- to fine-grained, commonly porphyritic, generally massive with well-developed columnar jointing, grading from basalt near contacts to fine-grained gabbro in the interior, composed of plagioclase and pyroxene with accessory opaques and locally devitrified glass, quartz, or olivine.

PorphyriticProject Gutenberg Self-Publishing eBooks

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Igneous Rock Textures Chemeketa Community College

Porphyritic Rocks (the two images below show a hand sample and a thin section of porphyritic aphanitic textured rocks)Porphyritic texture is really a subtype, but usage of the term often confuses the beginner. Porphyritic rocks are composed of at least two minerals having a conspicuous (large) difference in grain size.

ALEX STREKEISEN-Basalt-

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

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