An increase in ƒO2 exceeding 1 log unit from poikilitic to non-poikilitic textures implies degassing, with possible auto-oxidation, and/or crustal contamination. Igneous rocks. For the language, see Pontic Greek#Romeyka. 2. degree of crystal development: early formed crystals generally exhibit higher degree of development (i.e. g. interstitial . Poikilitic texture refers to igneous rocks where large component crystals contain smaller crystals of other minerals within them. Porphyry igneous rocks. These interpretations may also apply to the poikilitic‐textured Shaw chondrite, L‐group, which may owe its poikilitic texture to impact partial‐melting processes while in the parent body regolith. Intermediate igneous rocks. The largest ones are, by convention, more than about 3 cm long. For the language, see Pontic Greek#Romeyka. Poikilitic texture refers to crystals, typically phenocrysts, in an igneous rock which contain small grains of other minerals. Introduction & textures & structures of igneous rocks. (2) Poikilitic Texture. a microscopic crystal that is larger than the remainder of the groundmass . Porphyritic texture – rock has two porphyritic and poikilitic texture distinct grain sizes (usually composed of large grains porphyritic and poikilitic texture that are. Does this mean that the mineral occurs as smaller crystals surrounded by larger crystals of a different mineral, or is it the other way around? At this phenocryst fraction, grain-on-grain contact would make them extremely viscous. Usually the larger crystals, known as phenocrysts, formed earlier in the crystallisation sequence of the magma. English-Chinese geology dictionary (英汉地质大词典). b. porphyritic. Igneous rock textures. Ii. Poikilitic texture describes the occurrence of one mineral that is irregularly scattered as diversely oriented crystals within much larger host crystals of another mineral. porphyritic in nature containing K-feldspar megacrysts (up to 7 cm). I came across a description of a mineral having a "poikilitic texture", which to me is not very helpful. oikocryst. The porphyritic granites, including the hornblende- biotite granite and the biotite granite, are coarse-grained and have hypidiomorphic granular texture. Phenocryst & porphyritic textures | science trends. Poikilitic. Type of volcanic rock containing large porphyritic crystals of quartz. f. subophitic. Other articles where Seriate fabric is discussed: igneous rock: Fabric: …generally characterized either by a seriate fabric, in which the variation in grain size is gradual and essentially continuous, or by a porphyritic fabric, involving more than one distinct range of grain sizes. Both of these kinds of texture are common. 9th Dec 2020 16:46 UTC Erik Vercammen Expert. Types … The joints are filled with rough concrete and are 10 mm (0.4 inches) in width. In some rocks there seems to be little tendency for the minerals to envelop one another. e. ophitic. PORPHYRITIC TEXTURES. Topic . Alex strekeisen-poikilitic texture-. 8: Jungel metavolcanic suite (central India) predominantly known for: Best (a) Acidic basalt. pokilitic. A phenocryst is a large crystal that visually stands out compared to the rest of the minerals. A magma undergoes cooling slowly and due to certain environmental changes, it is pushed up out to the surface and hence subjected to fast cooling. c. glomeroporphyritic. Poikilitic is similar to these topics: Quartz-porphyry, Igneous textures, Granite and more. 3. The image represents a physical area of 1620 x 943 mm (63.8 x 37.1 inches) in total, with each individual block measuring approximately 400 x 100 mm (15.7 x 3.9 inches). 2005a). Keweenaw rift rocks include a somewhat rare textural variety of basalt called ophite or ophitic basalt. Igneous rocks textures. Euhedral minerals form before subhedral or unhedral one's . English-Chinese dictionary. Reading: how are igneous rocks classified? The texture is most easily observed in petrographic thin sections. Microphenocryst. Porphyritic texture in a trachite. A poikilitic texture is most easily observed in petrographic thin sections.. 22). a. seriate. Interpretation Translation  poikilitic texture 嵌晶状结构. Topics similar to or like Poikilitic. Representative data from 50 plagioclase micro- probe analyses are shown in Table 1. The poikilitic textural relationship in this view is akin to that of ophitic textures in dolerites; the poikilitic mineral grows fast from dispersed nuclei relative to the enclosed chadacryst mineral, which is either growing slowly from many nuclei, or, in this case, is dissolving owing to peritectic reaction with the melt to form orthopyroxene ( Fig. There are six main types of textures; phaneritic, aphanitic, porphyritic, glassy, pyroclastic and pegmatitic. 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