micas: flake off in thin sheets. potassium feldspar. Typically, quartz forms more than 60% of the rock, the rest being mostly feldspar although minor amounts of mica or amphibole may also be present. Felsic igneous rocks are silica rich and contain abundant potassium feldspar and quartz. Most of the rock is K-feldspar and quartz, and the dark crystals are a type of amphibole that is most common in felsic rocks. felsic. Mafic rocks are darker in color than felsic rocks. Felsic rocks are mostly feldspar (especially K-feldspar), at least 10% quartz, and less than 15% mafic minerals (biotite, hornblende). Felsic rocks Rocks composed mostly of biotite, muscovite, sodium-rich plagioclase feldspars, potassium feldspars, and quartz make up the felsic family of igneous rocks. What is the difference between felsic and mafic rocks? Composition Most Common Minerals Rock Name; felsic: glass (may contain a few minerals typical of felsic rocks) pumice: mafic: glass (may contain a few mineral typical of mafic rocks) Magma that has undergone a high degree of MAGMATIC DIFFERENTIATION has a composition consisting of FELSIC MINERALS (low temperature igneous minerals, such as quarts, K-spar, Na-spar, and mica. PLAY. Either in describing rocks or lava, mafic means that the lava or rock has less silica while felsic implies that the lava or rock has the most silica. mafic minerals. Felsic 3. Mafic obsidians are scarce, but they have the same appearance. Common felsic minerals include quartz, muscovite, hornblende, orthoclase, and the sodium rich plagioclase feldspars. Intermediate rocks are roughly even mixtures of felsic minerals (mainly plagioclase) and mafic minerals (mainly hornblende, pyroxene, and/or biotite). Felsic is an igneous rock term (it comes from combing parts of the words feldspar and silica) describing rocks forme from magma high in feldspars, silica and lighter colored materials. Felsic minerals are usually light in color and have specific gravities less than 3. If the K-feldspar is white, the granites are light gray; if the feldspar is pink or red, the granite is pink or red. You can't apply the term felsic to it. West of the lake, a large outcrop was investigated (Figure 4.17); it is a fine-grained, massive, featureless white felsic rock with 1-mm clear-quartz eyes. It is often assumed that phenocrysts that form the porphyritic texture must be felsic (feldspars (preferably alkali feldspars) or quartz). All granites contain quartz and K-feldspar. There is little or no quartz. mafic: Ca-plagioclase, pyroxene, olivine, amphibole: basalt: FROTHY TEXTURE (POROUS, PUMICEOUS) Originates in gas-charged volcanic eruptions, commonly pyroclastic. The most common felsic rock is granite. Mafic magma progressively crystallizes and evolves while minimizing thermal and rheological differences. The felsic minerals include quartz, tridymite, cristobalite, feldspars (plagioclase and alkali feldspar), feldspathoids (nepheline and leucite), muscovite, and corundum. calcite: hardness = 3 (not very hard), 3 cleavages not 90°, fizzes in dilute HCl. It is contrasted with mafic rocks, which are relatively richer in magnesium and iron.Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. potassium feldspar (k-spar): perthite (wavy lines) (The other general rock type is called mafic.) Which type of igneous rock would contain the most silica? Felsic <15% dark minerals: Very light in color, a bunch of quartz, potassium feldspar, very few dark minerals found. Mafic rocks are dominated by plagioclase and pyroxene (even if you can’t see them with the naked eye) and smaller amounts of olivine. Additionally, felsic magmas may have very high gas contents. quartz: hardness = 7 (hard), conchoidal fracture. Posted on August 31, 2014 by triplejunction. feldspars: hardness = 6 (hard), 2 cleavages at 90°. Felsic rocks are mostly feldspar (especially K-feldspar), at least 10% quartz, and less than 15% mafic minerals (biotite, hornblende). Mafic and Felsic minerals. Common felsic minerals include quartz, muscovite mica, and the orthoclase feldspars . Felsic igneous rocks are light in … Many parallel mafic and felsic bands are present in this area. Felsic rocks are commonly oversaturated and contain free quartz (SiO2), intermediate rocks contain little or no quartz or feldspathoids (undersaturated minerals), and mafic rocks may contain abundant feldspathoids. Mafic and Felsic, some igneous basics. mafic minerals. This one from Oahu is clearly not the most classic version of porphyry because it is mafic, it is extrusive, and the phenocrysts are mafic. Quartz: Quartz is a common mineral in many metamorphic and felsic igneous rocks that, like plagioclase, also has a non-metallic luster and hardness greater than glass. Igneous rock - Igneous rock - Mineralogical components: The major mineralogical components of igneous rocks can be divided into two groups: felsic (from feldspar and silica) and mafic (from magnesium and ferrous iron). felsic minerals (quartz, K feldspar, etc) are light colored while - felsic minerals have the lowest melting points (600 to 750 °C) Felsic magmas are much more viscous than the intermediate magmas. felsic. Learn vocabulary, terms, and more with flashcards, games, and other study tools. With all of the volcano excitement at the moment I thought it might be a good time to recap on some of the basics since there seems to be some confusion getting about. The term “felsic” refers to the high content of quartz laden feldspar minerals in the lava. muscovite: clear or light colored mica biotite: black (mafic) or dark colored mica. There is little or no quartz. Phaneritic ,Glassy 2. Felsic – 1202 – 1472 degrees Fahrenheit . Shale is a sedimentary rock. FELSIC ROCKS. felsic. See more. A large rheological difference between coeval felsic and mafic magmas inhibits much interaction. myrmekite rims with tiny quartz vermicules, intermeshed with tiny amphibole crystals. Felsic rocks are commonly oversaturated and contain free quartz (SiO 2), intermediate rocks contain little or no quartz or feldspathoids (undersaturated minerals), and mafic rocks may contain abundant feldspathoids. a. Mafic is a magma/rock that is rich in feldspar and silica (quartz), whereas felsic refers to that which is rich in Fe and Mg. Mafic or hybrid magmas inject into felsic magma at low volume fraction (0.65) of crystals. The mafic magma crystallized as a fine-grained mafic tonalite containing more than 30 volume percent biotite, and locally, the felsic magma crystallized as coarse-grained felsic tonalite in small, agmatitic patches and veins in the mafic tonalite. The flattening of the fragments in the mafic bands suggests that this exposure is in the hinge of a fold. Felsic minerals are usually light in color and have specific gravities less than 3.0. Intermediate rocks are roughly even mixtures of felsic minerals (mainly plagioclase) and mafic minerals (mainly hornblende, pyroxene, and/or biotite). Felsic igneous rocks are light-colored, so a felsic obsidian seems a paradox. This broad grouping on the basis of mineralogy related to silica content is used in many modern classification schemes. Intermediate: 15-40% dark minerals: In between dark and light in color. Minerals. In geology, felsic is an adjective describing igneous rocks that are relatively rich in elements that form feldspar and quartz. muscovite. ... quartz. Granite: Coarse-Grained Felsic Rock. Gabbros contain low silicon (no Quartz or Alkali feldspar) and essentially of ferromagnesian minerals and Plagioclase feldspar rich in calcium. The adjective mafic refers to a silicate mineral or rock (magmatic, either intrusive or extrusive) having a chemical composition rich in iron and magnesium and relatively poor in silicium. There is more … Most granites are light gray to pink in color, but gray and dark red granites are common, too. 5. Intrusive igneous rock, in which the mineral quartz is more than 90% of the rock's felsic mineral content, with feldspar at up to 10%. The amount of ferromagnesian minerals equals or exceeds that of Plagioclase. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Unlike plagioclase, however, quartz does not exhibit cleavage, which easily distinguishes it from feldspar minerals. Your logic is correct when looking at mineral stability in the face of chemical weathering. 1. Click to see complete answer.Correspondingly, is Granite felsic or mafic? plagioclase feldspar. The most common felsic rock is granite , which represents the purified end product of the earth's internal differentiation process. Intrusive 4. The most general classification is based on the relative abundance in a rock of felsic (feldspar and silica-quartz) minerals vs mafic( magnesium and ferrum or iron) minerals. Mafic lava creates basalt while felsic lava produces andesitic and rhyolite rocks. Which are definitions of “mafic” and “felsic”? STUDY. This prevalence is the reason why felsic minerals melt at lower temperatures than mafic ones. Granite This medium-grained rock is a plutonic rock. Mafic rocks are abundant in the Earth's crust beneath the oceans. a silicate mineral or igneous rock that is rich in magnesium and iron, and is thus a portmanteau of magnesium and ferric. It is contrasted with mafic rocks, which are relatively richer in magnesium and iron ().It refers to those rocks rich in silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Compilations of many rock analyses show that rhyolite and granite are felsic, with an average silica content of about 72 percent; syenite, diorite, and monzonite are intermediate, with an average silica content of 59 percent; gabbro and basalt are mafic, with an average silica content of 48 percent; and peridotite is Felsic definition, (of rocks) consisting chiefly of feldspars, feldspathoids, quartz, and other light-colored minerals. 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