which rock type is a coarse-grained mafic rock
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Gabbros: Coarse-Grained Mafic Rocks Gabbros: Coarse-Grained Mafic Rocks Gabbros are generally dark colored. They are dominated by Ca-rich plagioclase, which tends to be darker than the Na-rich variety, and by pyroxene. You may see olivine, but not in the samples shown here. This gabbro is roughly half pyroxene and half plagioclase. Pyroxene is typically duller and more blocky than hornblende, but most important are the cleavages intersecting at 90°. Click here to get a super-close up that shows the long, narrow rectangles (laths) typical of plagioclase. The striations are not visible in the photos. This gabbro has a lot of coarse, dark pyroxene crystals in it. There is also a lot of plagioclase, but it is tough to spot because it is also quite dark. The shiny cleavage planes in the upper park of this sample are all plagioclase.
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- Mafic and ultramafic magmas are high in dark, heavy minerals like pyroxene, amphibole, and olivine, which contribute to an igneous rock being dark in color with a higher speci … fic gravity than felsic and intermediate magmas and rocks. light colored igneous rock is more less dense and more felsic (which means the rock is mostly rich in silicon and aluminum). A dark colored igneous rock is more dense and ma … fic (which means the rocks are rich in iron and magnesium. 2 people found this useful. Paul Jones. 112,553 Contributions.
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Chapter 4 - Igneous Rocks light brown to gray, fine-grained extrusive igneous rock with a felsic composition. The extrusive equivalent of granite. FELSIC/EXTRUSIVE.
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- 1 Aphanitic igneous rocks have a fine-grained texture and most of their crystals are too small to see with the naked eye. 2  You will need to use a magnifying glass to observe the crystals in aphanitic rocks. 3  Igneous rocks that form too quickly for crystals to form have what is called a glassy texture. An example of an intrusive rock is granite. 2  When magma is above the earth's crust, it is known as lava. 3  Extrusive rocks form through very fast cooling of lava above the Earth's surface. 4  Extrusive rocks have very small, almost microscopic crystals.
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Lecture: Minerals in metamorphic rocks ï¿½ identity, stability, and textures By composition: Typically named in conjunction with a compositional type or mineral name if the minerals are known: mafic granulite, mica schist (or biotite schist), diopside hornfels, garnet amphibolite, quartzo-feldspathic gneiss.
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Plate Boundaries and Volcanoes Mafic rocks are rich in iron and magnesium. Why? Because the minerals from which they form are rich in iron and magnesium. Notice that mafic rocks are also high in density and dark in color and are the rocks found on the right side of 'scheme for igneous rock identifcation' (page 6).The rocks in the blue shaded area are mafic.ELSIC' is a term derived from the mineral feldspar. Both kinds of feldspar are rich in the minerals silicon (Si) and aluminum (Al). Felsic rocks are generally light in color and lower in density than mafic rocks.
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Pictures of Metamorphic Rocks Non-foliated metamorphic rocks such as hornfels, marble, quartzite, and novaculite do not have a layered or banded appearance. Pictures and brief descriptions of some common types of metamorphic rocks are shown on this page. Hornfels is a fine-grained nonfoliated metamorphic rock with no specific composition. It is produced by contact metamorphism. Hornfels is a rock that was baked while near a heat source such as a magma chamber, sill or dike. The specimen shown above is about two inches (five centimeters) across. Gneiss is foliated metamorphic rock that has a banded appearance and is made up of granular mineral grains.
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- In some cases gneisses are produced by higher grade metamorphism than schists. Low-grade metamorphic rocks tend to be fine-grained (the newly formed metamorphic mineral grains that is). High-grade metamorphic rocks tend to be coarse-grained. But grain size is also dependent on the grain size of the protolith.
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"Geological Terms Beginning With ""M""" Mafic. A term used to describe an igneous rock that has a large percentage of dark-colored minerals such as amphibole, pyroxene, and olivine. Also used in reference to the magmas from which these rocks crystallize. Mafic rocks are generally rich in magnesium and iron (think MAgnesium and FerrIC).
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- Alkali feldspar granite-a granitoid in which at least 90% of the total feldspar is in the form of alkali feldspar. Anorthosite-an intrusive igneous felsic rock composed predominantly of plagioclase. Aplite-a very fine grained intrusive igneous rock composed of quartz and feldspar.Basalt-a volcanic rock of mafic composition. Adakite-a class of basaltic rocks containing low amounts of yttrium and ytterbium. Hawaiite-a class of basalts formed from ocean island (hot spot) magmatism.plite-a very fine grained intrusive igneous rock composed of quartz and feldspar. Basalt-a volcanic rock of mafic composition. Adakite-a class of basaltic rocks containing low amounts of yttrium and ytterbium. Hawaiite-a class of basalts formed from ocean island (hot spot) magmatism.
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Rock types PICRITE is a mafic igneous rock similar to basalt but with more olivine. PORPHYRY is an igneous rock characterized by porphyritic texture. Porphyritic texture is a very common texture in igneous rocks in which larger crystals (phenocrysts) are embedded in a fine-grained groundmass.
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- Granite is an intrusive igneous rock (formed from the slow cooling of magma underground), the major component of the continental crust, coarse grained, and composed of quartz … along with a variety of feldspar minerals and micas. 12 people found this useful.ranite is hard to scratch with a fingernail.   2. Basalt is formed from lava that cooled rapidly, so it has a fine-grained texture. Its mineral grains are so tiny that they can be seen only through a microscope. It may be black or dark green. It contains the minerals feldspar and olivine.
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List of rock types Gneiss-a coarse grained metamorphic rock. Gossan-the product of the weathering of a sulfide rock or ore body. Granulite-a high grade metamorphic rock formed from basalt; also a facies of metamorphic rocks. Greenschist-a mafic metamorphic rock dominated by green amphiboles.
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Ask GeoMan... - Christine. There are several interconnected reasons. To set some ground rules: All of these are igneous rocks. Granite and rhyolite are considered felsic, while basalt and gabbro are mafic (click here for more information on mafic and felsic). Felsic rocks, in general, form the bulk of the continental plates, while mafic basalt forms the seafloor.
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Activity 3: Igneous Rocks The textural term used to describe a rock with large crystals is coarse-grained. In contrast, fine-grained rocks, such as basalt, are igneous rocks that have crystals too fine to see with the naked eye. Under magnification they are still very small but easily identifiable with a few optic tests.
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- Gneiss is a medium to course grained metamorphic rock.Shale is the typical parent rock. It is made up of clay minerals. Shale can metamorphose into slate, phyllite, schist or gneiss depending on the degree of heat and pressure. Gneiss has the greatest degree of metamorphism in this group.t is made up of clay minerals. Shale can metamorphose into slate, phyllite, schist or gneiss depending on the degree of heat and pressure. Slate is the least metamorphosed of this group. Meaning that it has been subjected to the least amount of heat and pressure (low-grade metamorphism).
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Chapter 4: Igneous Rocks Mafic is a magma/rock that is rich in Fe and Mg, whereas felsic refers to that which is rich in feldspar and silica (quartz). c. Mafic is hard rock, felsic is soft rock. Both a. and c. None of these.
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What is the definition of mafic? Rockhound. Mafic is a term used to describe an igneous rock that is usually dark in color, with a chemistry that may be high in magnesium and iron, like basalt. Mafic is also a term used to describe a type of magma that is high in calcium, magnesium and iron, and relatively low in silica, compared to felsic magma.afic is also a term used to describe a type of magma that is high in calcium, magnesium and iron, and relatively low in silica, compared to felsic magma.
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- Mafic magma will cool and crystallize to produce the volcanic rock basalt, whereas felsic magma will crystallize to produce dacite and rhyolite. Intermediate-composition magmas will crystallize to produce the rock andesite.
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- Alkali feldspar granite-a granitoid in which at least 90% of the total feldspar is in the form of alkali feldspar. Anorthosite-an intrusive igneous felsic rock composed predominantly of plagioclase. Aplite-a very fine grained intrusive igneous rock composed of quartz and feldspar. Basalt-a volcanic rock of mafic composition. Adakite-a class of basaltic rocks containing low amounts of yttrium and ytterbium. Hawaiite-a class of basalts formed from ocean island (hot spot) magmatism. Basanite-a volcanic rock of mafic composition; essentially a silica-undersaturated basalt.
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- Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite has a medium to coarse texture, occasionally with some individual crystals larger tha … n the groundmass forming a rock known as porphyry.Granites can be pink to dark gray or even black, depending on their chemistry and mineralogy. Outcrops of granite tend to form tors, and rounded massifs.ranite is hard to scratch with a fingernail.   2. Basalt is formed from lava that cooled rapidly, so it has a fine-grained texture. Its mineral grains are so tiny that they can be seen only through a microscope. It may be black or dark green. It contains the minerals feldspar and olivine.
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Ultramafic rock Metamorphism of ultramafic rocks in the presence of water and/or carbon dioxide results in two main classes of metamorphic ultramafic rock; talc carbonate and serpentinite.
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- Pictures and brief descriptions of some common igneous rock types are shown on this page. Diorite is a coarse-grained, intrusive igneous rock that contains a mixture of feldspar, pyroxene, hornblende and sometimes quartz. The specimen shown above is about two inches (five centimeters) across.
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Mafic rock Mafic rock, in geology, igneous rock that is dominated by the silicates pyroxene, amphibole, olivine, and mica. These minerals are high in magnesium and ferric oxides, and their presence gives mafic rock its characteristic dark colour. Mafic rock is commonly contrasted with felsic rock, in which light-coloured minerals predominate. Common mafic rocks include basalt and its coarse-grained intrusive equivalent, gabbro.
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Ask GeoMan... Mafic minerals are usually dark in color and have relatively high specific gravities (greater than 3.0). Common rock-forming mafic minerals include olivine, pyroxene, amphibole, biotite mica, and the plagioclase feldspars.Mafic magmas are usually produced at spreading centers, and represent material which is newly differentiated from the upper mantle. Common mafic rocks include basalt and gabbro.ommon rock-forming mafic minerals include olivine, pyroxene, amphibole, biotite mica, and the plagioclase feldspars. Mafic magmas are usually produced at spreading centers, and represent material which is newly differentiated from the upper mantle. Common mafic rocks include basalt and gabbro.
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- Aplite-a very fine grained intrusive igneous rock composed of quartz and feldspar. Basalt-a volcanic rock of mafic composition. Adakite-a class of basaltic rocks containing low amounts of yttrium and ytterbium. Hawaiite-a class of basalts formed from ocean island (hot spot) magmatism.