Intrusive igneous rocks are formed from magma that cools and solidifies within the crust of a planet, surrounded by preexisting rock (called country rock); the magma cools slowly and, as a result, these rocks are coarsegrained. The mineral grains in such rocksFelsic and mafic rocks. Chemical analyses of the most abundant components in rocks usually are presented as oxides of the elements; igneous rocks typically consist of approximately 12 major oxides totaling over 99 percent of the rock. Of the oxides, silica (SiO 2) is usually the most abundant. felsic igneous rocks generally contain
Scale box is in millimeters. In order for a rock to be classified as felsic, it generally needs to contain more than 75 felsic minerals; namely quartz, orthoclase and plagioclase. Rocks with greater than 90 felsic minerals can also be called leucocratic, meaning 'lightcoloured
Remember, felsic rocks are generally light colored because they contain an abundance of quartz and potassium feldspar (usually pink colored to white); mafic rocks are dark colored because they do not contain quartz or lightcolored feldspar and contain an abundance of darkcolored ironmagnesium minerals, including pyroxene. Felsic igneous rocks, as a whole rock, tend to have light colors or shades: white, pink, light brown, light gray. Mafic igneous rocks, on the whole, tend to be dark colored, commonly black or dark gray. Most mafic magma originates by melting of rocks in the mantle that are extremely rich in iron and magnesium.felsic igneous rocks generally contain Start studying GEOL 101 Chapter 4: Magma, Igneous Rocks and Intrusive Activity. Learn vocabulary, terms, and more with flashcards, games, and other study tools.
Felsic rocks have a higher silica content (65 to 75), so they are generally harder, lighter in color, are enriched in elements such as sodium and potassium and may contain quartz (if the silica content is high enough, the rock is oversaturated in silica i. e. theres more SiO2 available than can be taken up in minerals like alkaline feldspar, so felsic igneous rocks generally contain Felsic rocks, similar to acidic rocks, contain a lot of silica, sodium and calcium and form quartz and feldspar minerals; felsic is short for feldsparsilica. Mafic, similar to basic rocks, have a lot of magnesium and iron (ferrous) and is short for magnesiumferrous. Jan 04, 2019 Igneous rocks constitute one of the three principal classes of rocks, the others being metamorphic and sedimentary. Igneous rocks are formed from the solidification of magma, which is a hot (600 to 1, 300 C, or 1, 100 to 2, 400 F) molten or partially molten rock material. Which igneous rock cooled slowly under ground and contains mostly quartz and potassium feldspar? A. Granite. As igneous rocks become more mafic, they also become (color) felsic igneous rocks generally have a color. light. Mafic igneous rocks generally have a density. high