Groundmass may be coarse-grained (phaneritic), fine-grained (aphanitic), or even glassy or microcrystalline. For granite porphyry, it is coarse-grained. In most cases, a porphyritic granite rock will have pinkish-to-whitish potassium feldspar phenocrysts set in a phaneritic groundmass. However, there could be other phenocrysts, such as quartz ...
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Porphyritic Texture Porphyritic (Intrusive and Extrusive) Porphyritic rocks contain both coarse- and fine-grained textures indicating different environmental conditions which formed the rock. The coarse grains in a porphyritic rock develop as the magma is cooling below the surface of the earth. The fine-grained component of a porphyriic
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Basalt has several textural varieties such as glassy, massive, porphyritic, vesicular, scoriaceous. In the Keweenaw we can subdivide textures into three types, following Huber's example: Porphyrite, Trap and Ophite, applies ideally to Isle Royale, but works for the PLV on the Keweenaw too.
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Aphanitic: Fine-grained texture due to rapid cooling (typical of volcanic rocks). Basalt is a classic example of an aphanitic igneous rock. The crystals are so small that they are often not visible to the naked eye. Porphyritic: Contains both large and small crystals, indicating a complex cooling history. Porphyritic andesite is a rock that ...
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Porphyritic texture Porphyritic texture is an igneous rock texture in which large crystals are set in a finer-grained or glassy groundmass. Porphyritic textures occur in coarse, medium and fine-grained igneous rocks. Usually the larger crystals, known as phenocrysts, formed earlier in the crystallisation sequence of the magma.
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Fine-Grained Texture: Basalt, cooled quickly at the surface, has small, barely visible grains. Coarse-Grained Texture: Gabbro, formed slowly underground, displays larger crystals. Porphyritic Texture: Porphyritic basalt …
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Igneous textures include the rock textures occurring in igneous rocks.Igneous textures are used by geologists in determining the mode of origin igneous rocks and are used in rock classification. There are seven main types of textures: phaneritic, aphanitic, porphyritic, glassy, vesicular, pyroclastic and pegmatitic. When magma cools slowly underground …
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Type Igneous Rock Texture Porphyritic Origin Extrusive/Volcanic Chemical Composition Mafic Color Dark Gray to Black Mineral Composition Calcium Plagioclase, …
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Trachyte is a type of volcanic rock that falls within the category of extrusive igneous rocks. It is characterized by its unique composition and texture, which make it distinct from other volcanic rocks like basalt, andesite, and rhyolite. Trachyte gets its name from the Greek word "trachys," which means rough, reflecting the rock's typically rough …
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All basalt is fine-grained, meaning that you cannot see the individual crystals in the rock. This texture is known as 'aphanitic ... As I mentioned above, basalt is very often 'porphyritic ...
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A mafic rock is gabbro if it is course-grained, and basalt if fine-grained. The course-grained version of an ultramafic rock is peridotite, ... An igneous rock with crystals of distinctly different size (Figure 4.14) is said to have a porphyritic texture, or might be referred to as a …
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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 …
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This rock displays a fine-grained, porphyritic texture. The relatively small olivine phenocrysts are more clearly displayed in the close-up photo below.
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There are six main types of textures; phaneritic, aphanitic, porphyritic, glassy, pyroclastic and pegmatitic. Aphanitic (a = not, ... not just part of it as in a porphyritic, fine-grained igneous rock. The texture of an igneous rock made up entirely of crystals big enough to be easily seen with the naked eye is phaneritic. ... Basalt with fewer ...
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Porphyritic is used as an adjective to modify the name of any fine-grained igneous rock that has less than 50% phenocrysts in it. Example: Porphyritic basalt, porphyritic andesite. Porphyry is used as a noun after the rock name if more than 50% of the rock is made of phenocrysts. Example: Basalt porphyry.
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Which mineral would you expect to see as a phenocryst in a porphyritic basalt? A) olivine B) quartz C) orthoclase D) sodium-rich plagioclase and more. Study with Quizlet and memorize flashcards containing terms like Lava flows are typically finer grained than intrusive igneous rocks.
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Andesite is a fine-grained, extrusive igneous rock composed mainly of plagioclase with other minerals such as hornblende ... Some cool so quickly that they form an amorphous glass. These rocks include: andesite, basalt, dacite, obsidian, pumice, rhyolite, scoria, and tuff. Pictures and brief descriptions of some common igneous rock types are ...
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A mafic rock is gabbro if it's course-grained, and basalt if fine-grained. The course-grained version of an ultramafic rock is peridotite, ... An igneous rock with crystals of distinctly different size (Figure 7.14) is said to have a porphyritic texture, or might be referred to as a …
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Figure 4.4: Basalt is a classic fine-grained extrusive igneous rock. ... When porphyritic, it often has either olivine or plagioclase phenocrysts. Basalt is the main rock which is formed at mid-ocean ridges, and is therefore the most common rock on the Earth's surface, making up the entirety of the ocean floor (except where covered by ...
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Porphyritic. Which igneous ... Basalt is the fine-grained equivalent of gabbro. (true or false). have a similar texture. Granite and gabbro _____. have a similar texture have a similar mineral composition are not similar in either texture or mineral composition are similar in both texture and mineral composit.
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Porphyritic – The texture of an igneous (volcanic or plutonic) rock that contains large crystals (phenocrysts) in a fine-grained groundmass. Photo (right): Porphyritic rhyodacite, Lassen Volcano …
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Basalt is a common and widely used, fine-grained, dark-colored mafic volcanic rock. It has mainly calcic plagioclase feldspar and augite.
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Basalt is a fine-grained and dark-colored rock. Black color is given to basalt by pyroxene group mineral augite. Width of the sample is 12 cm. ... but some basaltic rocks are porphyritic (lots of porphyritic rocks can be seen here: porphyry) and show some of these minerals nicely (unfortunately not magnetite, though).
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Many rocks with an overall fine-grained texture display scattered minerals that are more than 1 mm across. This porphyritic texture indicates that the magma sat and cooled a bit below the Earth's surface, thus giving time for the large crystals to grow, before erupting onto the surface and cooling very quickly. The large crystals are termed phenocrysts …
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The porphyritic texture is an igneous rock texture with large crystals in a finer-grained matrix. How does it form and what does it indicate?
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Igneous rocks showing the porphyry texture are said to be porphyritic. It is a more accurate term, considering it is an adjective. For instance, you can have porphyritic andesite, rhyolite, granite, basalt, diorite, phonolite, etcetera. Lastly, the abundant phenocrysts' names may precede the rock type in naming porphyritic stones or rocks.
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The presence of large crystals in a fine-grained groundmass is commonly regarded to indicate that the phenocrystals crystallized slowly during magma ascent or in a magma chamber, before the crystallization of the surrounding matrix. ... Porphyritic volcanic rocks. Porphyritic basalt with phenocrysts of plagioclase (white). The sample is 8 cm ...
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Porphyritic basalt showing a euhedral clinopyroxene phenocryst with marginal alteration to chlorite set in a fine-grained groundmass of randomly orientated plagioclase microlites and recrystallised glass.
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Basalt rocks are a common geological formation that plays a crucial role in various engineering applications, such as construction, infrastructure development, and geotechnical engineering.
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