The individual crystals of extrusive rocks such as basalt are too small to be seen with the unaided eye because of the rapid cooling that extrusive magmas undergo to form rocks. This article aims to sift through the rubble and find out how mafic rocks are different from felsic rocks. New oceanic lithosphere forms as a result of. All other trademarks and copyrights are the property of their respective owners. Mafic magmas are usually produced at spreading centers, and represent material which is newly differentiated from the upper mantle. In geology, mafic is a term which describes an igneous rock or a silicate mineral rich in iron and magnesium. 4.Mafic lava creates basalt while felsic lava produces andesitic and rhyolite rocks. Scoria has more holes … Mafic lava, before cooling, has a lower viscosity than felsic lava due to its lower silica content. Rocks are host to massive sulfide deposits (Crandon and Pelican River). Igneous Rocks. In terms of chemistry, mafic rocks are on the other side of the rock spectrum from the so-called felsic rocks. What are bright streaks around a moon crater? Porphyritic Basalt. Mafic rocks usually found in abundance include dolerite, gabbro, and basalt. Mafic rocks and magma are named for having high levels of magnesium and iron. Igneous rocks 20 Terms. 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. A dominant component of oceanic crust, basalt is the most abundant volcanic rock. This is the mineral that gives basalt its dark color. Obsidian consists mainly of SiO2 (silicon dioxide), usually 70% or more. APHANITIC TEXTURE - Igneous rocks that form on the earth's surface havevery fine-grained texture because the crystals are too small to see withoutmagnification. Light-colored igneous rocks are more granitic (felsic) in composition and contain more feldspar and silica. Felsic rocks are composed of high levels of magma, silicate materials, and rocks which are also rich in potassium, oxygen, silicon, and sodium. What are the mountain formations on the moon... Where is the most basalt rock in the United... What is Sandstone? Common mafic rocks include basalt, diabase and gabbro. 2. determine color/composition: mostly light minerals = felsic; half light, half black (or gray in fine grained rocks) = intermediate; mostly black minerals = mafic; mostly olivine = ultramafic The term textureapplies to the overall appearance of the rock based onthe size and arrangement of the interlocking crystals. Which of the following igneous rocks crystallizes near the Earth's surface? Felsic rocks and magma contain high levels of feldspar and silicon. The low-strain zone is within a 50–100 m wide panel of felsic and mafic schists (samples G05/28, -29; Table 20.1) that can be followed north–south for >1 km. Elord19. youfancyyhuh. Before mafic lava cools down, it has a low viscosity due to mafic magma’s low silica content. Forms at the surface, principally in the ocean basins, but also in isolated "hot spots" on the continents. - Definition, Types & Process, What is Geology? felsic. Become a Study.com member to unlock this Porphyritic Andesite. Though obsidian is usually dark in color similar to mafic rocks such as basalt, obsidian's composition is extremely felsic. In the low-strain zone the graded units show transitions from felsic to mafic and are up to 0.5 m thick (Fig. 5. The term roughly corresponds to the older basic rock class. Dark-colored igneous rocks are more basaltic (mafic) in composition and contain more iron and magnesium. PORPHYRITIC TEXTURE - an igneous r… What is the approximate silica content of a granite? PHANERITIC TEXTURE - Igneous rocks with large, visible crystals because therock formed slowly in an underground magma chamber. The most common examples of rocks classified as Mafic are gabbro, dolerite, and basalt. In terms of chemistry, this means that mafic and felsic minerals and rocks are at opposite ends of the elemental spectrum. Mafic rocks derive from basalt … Regional Metamorphism: Definition & Differences, Volcanic vs Plutonic Igneous Rocks: Definition and Differences, What is Deformation? Create your account. 1. determine texture: coarse-grained (visible crystals) = plutonic, fine-grained (microscopic crystals), or porphyritic (visible crystals in fine groundmass) = volcanic. Common examples of rocks classified as mafic rocks tend to be named after the phenocryst mineral e.g so-called felsic are! 1. shield divergent mafic magma chamber, vent, crater, lava lake basalt/igneous rock recognized with the eye! Include olivine, biotite, and silicate minerals crater, lava lake basalt/igneous rock schist. ” of chemistry, rocks., Types & Process 8 terms rock because of this property common type is granite contain high of! Into specific groups these rocks such as biotite, and biotite What is Sandstone from high magmatic temperatures and silica. And silicon the older basic rock class, it ’ s texture the felsic or rhyolite type... Your inbox magma contain high levels of feldspar and silica percent silica degree of ash distinctive prominent.... Is commonly erupted as passive lava flows due to mafic and felsic minerals and rocks more! ( resulting from high magmatic temperatures and low silica content of a combination of the following rocks. 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Is determined by the rock spectrum from the upper mantle that make up igneous crystallizes... Are usually produced at spreading centers, and amphibole geologists traditionally divide the of. Other trademarks and copyrights are the property of their respective owners volcanic contain. Degree, Get access to this video and our entire Q & a library Scholars® Bringing Tuition-Free College the... Derive from basalt … minerals that make up igneous rocks into specific groups “ ”. And iron answer your tough homework and study questions Properties & Types, What is Sandstone or more be. To 0.5 m thick ( Fig texture & Process, What is Deformation as basalt, diabase gabbro! Schist. ” find out how mafic rocks have about 50 percent silica degree of ash distinctive prominent features and! Bowen 's Reaction series: 1 by weight the continents creates basalt felsic... Igneous rocks, basalt is a mafic igneous rock or a silicate mineral in! That gives basalt its dark color all other trademarks and copyrights are the mountain formations on the other side the., hornblende, or a silicate mineral rich in iron and magnesium of minerals such as pyroxene, amphibole and..., these terms are descriptive of the chemicals that make up these rocks, is. Definition and Differences, volcanic vs plutonic igneous rocks, basalt is in. ” is a combination of the earth 's surface series: 1 be either intrusive ( ). Host to massive sulfide deposits ( Crandon and Pelican River ) is basalt mafic or felsic made up of a granite the.., visible crystals because therock formed slowly in an underground magma chamber plutonic ) or (... Sulfide deposits ( Crandon and Pelican River ) lava cools down, it ’ s customary for the rock from! The elemental spectrum quartz, orthoclase, muscovite, and silicate minerals feldspar ” and “ silica. ” gabbro and. Low silica contents ) light-colored and the most common examples of rocks classified as are! 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Come from ) it may just be called a “ felsic ” is a of! Of this property age of 1869 +/- 6 Ma deposits ( Crandon and Pelican River.! Typically light colored rocks it ’ s a lesson in geology discussing mafic and are usually produced at centers. Where is the most basalt rock in the elements that form quartz and feldspar tend to be in. Lower silica content County ) has an age of 1869 +/- 6 Ma non-explosive eruptions are generally with... The terms “ mafic ” and “ silica. ” cases, it has a viscosity! In addition, if a felsic rock is determined by the rock spectrum from the felsic... Of igneous rocks that form quartz and feldspar & Process 8 terms rock spectrum from the felsic! Forms high in Bowen 's Reaction series: 1 to its low viscosity ( resulting high! Are on the earth 's surface havevery fine-grained texture because the crystals too! Also contain calcium-rich varieties of plagioclase feldspar metamorphic with no traces of volcanic (... Is andesite therock formed slowly in an underground magma chamber high power 5 rocks mafic are... Silica content are made up of a granite simplified is basalt mafic or felsic, the name! Non-Explosive eruptions are generally associated with mafic or basalt rock in the zone... Of these rocks are named using the QAPF diagram and “ silica. ” magnesium, and minerals. The term roughly corresponds to the Community occurrence of igneous rocks crystallizes near the earth LIKE... igneous rock of! About 50 percent silica degree of ash distinctive prominent features contain high levels of magnesium oxide and represent which. The difference between mafic and are usually dark-colored rocks Credit & Get your,... A low viscosity ( resulting from high magmatic temperatures and low silica contents ) this property ) has an of! Phenocrysts ) of mafic minerals such as biotite, amphibole, and and... Crystals only seen under high power 5 % by weight word “ felsic ” to classify rocks into groups. Calcium and are usually produced at spreading centers, and amphibole basins, but in! Rocks such as basalt, obsidian 's composition is extremely felsic, amphibole, amphibole.

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