What mineral composition is most characteristic of mafic rocks? olivine, pyroxene, and calcium-rich plagioclase What mineral composition is most characteristic of intermediate rocks? sodium-rich plagioclase and hornblende with some quartz or biotite
Rock Sample #4 Rhyolite It formed quickly on the surface from felsic lava Rock Sample#5 obsidian Rock Sample #6 pumice formed from felsic lava as gas bubbles escaped Rock Sample #7 diorite a phaneritic texture crystallized from an intermediate magma
A porphyritic rock forms when there is a period of slow cooling, followed by more rapid cooling. A porphyritic rock contains both ________ and __________. phenocrysts; groundmass Rock Sample #1 Granite formed slowly underground from felsic magma Rock Sample #2 granite phaneritic texture crystallized from felsic magma Rock Sample #3 Tuff
Felsic rocks are mostly feldspar (especially K-feldspar), at least 10% quartz, and less than 15% mafic minerals (biotite, hornblende).
Felsic magma or lava is higher in viscosity than mafic magma/lava. Felsic rocks are usually light in color and have specific gravities less than 3. The most common felsic rock is granite. Common felsic minerals include quartz, muscovite, orthoclase, and the sodium-rich plagioclase feldspars (albite-rich).
Common felsic minerals include quartz, muscovite mica, and the orthoclase feldspars. The most common felsic rock is granite, which represents the purified end product of the earth's internal differentiation process.
GraniteFelsic Composition Granite is a course-crystalline felsic intrusive rock. The presence of quartz is a good indicator of granite. Granite commonly has large amounts of salmon pink potassium feldspar and white plagioclase crystals that have visible cleavage planes.
continental crustFelsic rocks are mostly found within and on Earth's continental crust because of the lighter and less dense elements and minerals that compose them.
In a widely accepted silica-content classification scheme, rocks with more than 65 percent silica are called felsic; those with between 55 and 65 percent silica are intermediate; those with between 45 and 55 percent silica are mafic; and those with less than 45 percent are ultramafic.
Felsic igneous rocks are silica rich and contain abundant potassium feldspar and quartz.
Felsic rocks are rich in Silicon, Sodium, and Potassium, while Mafic igneous rocks are rich in Iron, Magnesium, and Calcium. Felsic rocks are lighter in color, whereas Mafic rocks are darker in color. Depending on the cooling process, felsic and mafic rocks can have fine or coarse textures.
First, as we've already discussed, felsic magmas tend to be more viscous because they have more silica, and hence more polymerization. Second, felsic magmas tend to have higher levels of volatiles; that is, components that behave as gases during volcanic eruptions.
Felsic rocks are igneous rocks that are rich in feldspar and silicon. The word 'felsic' was made up from parts of those words. Because they are made of lighter elements, they tend to be more buoyant than mafic rocks, which are rocks high in magnesium and iron, like basalt. Granite is the most common felsic rock.
Definition of felsic : consisting of or chiefly consisting of feldspar or feldspathoid quartz.
Granite and rhyolite are considered felsic, while basalt and gabbro are mafic (click here for more information on mafic and felsic).