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FAQ: What is Ophitic texture?

Ophitic texture is the association of lath-shaped euhedral crystals of plagioclase, grouped radially or in an irregular mesh, with surrounding or interstitial large anhedral crystals of pyroxene; it is characteristic of the common rock type known as diabase.

Which rock shows ophitic texture?

This texture is found in granites. Ophitic texture – laths of plagioclase in a coarse grained matrix of pyroxene crystals, wherein the plagioclase is totally surrounded by pyroxene grains. This texture is common in diabases and gabbros.

How is ophitic texture formed?

Ophitic texture, a variant the poikilitic texture, is one where random plagioclase laths are enclosed by pyroxene or olivine. If the cooling rate is very fast, the interstitial material between plagioclase laths may be quenched to glass to form an intersertal texture.

Is ophitic texture found in peridotite?

Ophitic. A variety of poikolitic texture, known as ophitic texture, is very characteristic of many diabases, in which large crystals of augite enclose smaller laths of plagioclase feldspar. Biotite and hornblende frequently enclose feldspar ophitically; less commonly iron oxides and sphene do so.

What is Poikilitic texture in geology?

Poikilitic texture refers to crystals, typically phenocrysts, in an igneous rock which contain small grains of other minerals. In igneous rocks Poikilitic texture is widely used to determine order of crystallization; if one mineral is enclosed by another then the enclosed grain must have been the first to crystallize.

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What is Holocrystalline texture?

Said of the texture of an igneous rock composed entirely of crystals, i.e., having no glassy part. Also, said of a rock with such a texture.

What is Panidiomorphic texture?

Panidiomorphic refers to a texture in which, theoretically all the component mineral grains are subhedral. Allotriomorphic refers to a texture in which all the component mineral grains are anhedral.

What are the 5 textures of igneous rocks?

Igneous Rock Textures Igneous textures are used by geologists in determining the mode of origin of igneous rocks and are used in rock classification. There are six main types of textures; phaneritic, aphanitic, porphyritic, glassy, pyroclastic and pegmatitic.

What is a Phenocrysts in geology?

A relatively large crystal embedded in a finer-grained or glassy igneous rock. The presence of phenocrysts gives the rock a porphyritic texture (see illustration). Phenocrysts are represented most commonly by feldspar, quartz, biotite, hornblende, pyroxene and olivine.

What is Granophyric texture?

A granophyric texture is an intergrowth of quartz and alkali feldspar in an igneous rock that is less well defined than a graphic texture and often is somewhat radiating. Granophyric texture can be similar to micrographic texture and to the coarser graphic intergrowths of quartz and alkali feldspar common in pegmatite.

What is the texture of sedimentary rocks?

Texture: Sedimentary rocks may have clastic (detrital) or non-clastic texture. Clastic sedimentary rocks are composed of grains, fragments of pre-existing rocks that have been packed together with spaces (pores) between grains.

What is Poikiloblastic texture?

i. Said of a metamorphic texture in which small grains of one constituent lie within larger metacrysts. Modern usage favors this meaning. Synonym of: sieve texture.

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What is graphic texture in geology?

A graphic texture is an igneous rock texture in which an intergrowth of two minerals has the appearance of runic writing. Graphic textures are most commonly intergrowths of quartz and alkali feldspar in which the quartz appears as v-shaped inclusions enclosed by the feldspar.

What is Intersertal texture?

Intersertal is a textural term used to denote that the angular spaces between larger crystals is occupied by glass, or glass and small crystals. The glass may be devitrified or altered to other phases.

What is Panidiomorphic?

/ (pæˌnɪdɪəʊˈmɔːfɪk) / adjective. (of igneous rocks) having well-developed crystals.

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