They are roughly even mixtures of felsic minerals and mafic minerals.
Igneous rocks contain the following common minerals: Plagioclase feldspar, Olivine, Potassium feldspar, Pyroxene, Quartz, Amphibole, Biotite, and Muscovite. The percentage of these minerals present in an igneous rock determines whether it is felsic, intermediate, mafic, or ultramafic. On the other hand an Intrusive igneous rock cools very slowly beneath the surface and is created by magma. Since the cooling process is very slow intrusive igneous rocks have very large crystals (coarse grained). In some instances there is also a third type of igneous rock. Igneous Rocks by Composition Igneous rocks are classified according to their mineral content: Ultramafic rocks are dominated by olivine and/or pyroxene. Mafic rocks are dominated by plagioclase and pyroxene (even if you can't see them with the naked eye) and smaller amounts of olivine. Intermediate rocks are roughly even mixtures of felsic minerals (mainly plagioclase) and mafic minerals (mainly hornblende, pyroxene, and/or biotite). There is little or no quartz. Felsic rocks are mostly feldspar (especially K-feldspar), at least 10% quartz, and less than 15% mafic minerals (biotite, hornblende) intermediate rock An igneous rock with a chemical composition between those of basic and acid rocks. The limits are not fixed rigidly. Cite this article. Pick a style below, and copy the text for your bibliography. MLA. Chicago. APA. MICHAEL ALLABY.  intermediate rock. . . 2004. intermediate rock Igneous rock whose chemical composition lies between those of basic and acidic rocks, e.g. andesite. The limits are not fixed rigidly and a number of schemes exist that are based on modal mineralogy and the whole rock chemistry (see MODAL ANALYSIS). Compare ACID ROCK; and BASIC ROCK. In igneous petrology an intermediate composition refers to the chemical composition of a rock that has 52-63 wt% SiO2 being an intermediate between felsic and mafic compositions. Typical intermediate rocks include andesite, dacite and trachyandesite among volcanic rocks and diorite and granodiorite among plutonic rocks.  An Igneous rock is the product of cooled solidified magma/lava. As magma/lava cools it goes through the process of crystallization which turns it into an igneous rock. The amount of time it takes for an igneous rock to form depends on its location and its composition. On the other hand an Intrusive igneous rock cools very slowly beneath the surface and is created by magma. Since the cooling process is very slow intrusive igneous rocks have very large crystals (coarse grained). In some instances there is also a third type of What is INTERMEDIATE IGNEOUS ROCKS? Igneous rocks containing from 55% to 66% silica, and essentially intermediate in composition between the acid granitic and basic gabbroic or basaltic rocks. See diorite, syenite, syenodiorite.  Generalized terms used in this classification technique include felsic, intermediate, mafic and ultramafic. Felsic rocks, similar to acidic rocks, contain a lot of silica, sodium and calcium and form quartz and feldspar minerals; felsic is short for feldspar/silica. When magma flows onto the surface of the Earth it is called lava. When the lava cools and forms a rock, that rock is an igneous rock. But there are also rocks that form from magma that does not reach the surface of the Earth. These rocks form in what are often called plutons and are also types of igneous rocks. Igneous rocks are classified according to their mineral content: 1  Ultramafic rocks are dominated by olivine and/or pyroxene. 2  Mafic rocks are dominated by plagioclase and pyroxene (even if you can't see them with the naked eye) and smaller amounts of olivine. Intermediate rocks are roughly even mixtures of felsic minerals (mainly plagioclase) and mafic minerals (mainly hornblende, pyroxene, and/or biotite). There is little or no quartz. Felsic rocks are mostly feldspar (especially K-feldspar), at least 10% quartz, and less than 15% mafic minerals (biotite, hornblende). igneous rock containing 56–65 percent silica. This category includes primarily feldspathic rocks with small admixtures of such ferromagnesian minerals as pyroxene, hornblende, and, more rarely, biotite. Intermediate plagioclases (oligoclase, andesine) are typical of feldspars. According to the weight percentage of the constituents of intermediate rocks, a distinction is made between the sodium series (diorites, andesites, andésites) porphyrites and the calcic (series, syenites). trachytes Intermediate rocks are found mainly among extrusive rocks in which andesites andésites and porphyrites predominate over trachytes and; porphyries the intrusive (rocks, diorite) syenite are much less widely. distributed
http://www.arch.dcr.state.nc.us/ncarch/GeoArcheo/IgneousA.htm http://www.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousCompositions.html http://www.encyclopedia.com/topic/intermediate_rock.aspx https://en.wikipedia.org/wiki/Intermediate_composition http://www.arch.dcr.state.nc.us/ncarch/GeoArcheo/IgneousA.htm http://thesciencedictionary.org/intermediate-igneous-rocks/ http://www.galleries.com/rocks/igneous.htm http://www.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousCompositions.html http://encyclopedia2.thefreedictionary.com/Intermediate+Rock
what are intermediate rocks