For similar determinations, glasses can also be prepared in the laboratory from crystalline rocks. Due to the color of the minerals forming them, the rocks are either light or dark. Click to see full answer People also ask, is rhyolite felsic or mafic or intermediate? Felsic rocks have a much higher proportion of silica (>63%) Mafic rocks have a lower proportion of silica (20-40%) Pretty much all differences in the characteristics of the 2 rock groups are caused by this difference; colour, nature of eruptions, melting point, etc etc. Mafic minerals also crystallize at higher temperatures than felsic minerals. Felsic rocks are mostly light-colored and the most common type is granite. Felsic lavas are low temperature lavas because lower temperatures are required to keep felsic minerals molten (and if it was hotter it would have incorporated more iron and magnesium in comparison to silica). Felsite is a petrologic field term used to refer to very fine-grained or aphanitic, light-colored volcanic rocks which might be later reclassified after a more detailed microscopic or chemical analysis. Felsic rocks can be produced by metamorphism of both igneous and sedimentary protoliths (e.g., granite and arkose, respectively) and are rich in silicon, sodium (Na), potassium, calcium, aluminum, and lesser amounts of iron and magnesium. Obsidian is a naturally occurring volcanic glass. Mafic lava creates basalt while felsic lava produces andesitic and rhyolite rocks. Although it doesn’t have a silica content that is as high as felsic magma, intermediate magma is roughly 60% silica, so it still contains a lot of silica. There are examples known of highly sheared granites which can be mistaken for rhyolites. Felsic rocks are rich in silica, potassium, sodium, and aluminum and contain only small amounts of iron, magnesium, and … Increases as silica content increases. Felsic magmas are higher in silica and contain lighter colored minerals such as quartz and orthoclase feldspar. This broad grouping on the basis of mineralogy related to silica content is used in many modern classification schemes. 4.3 What are the 6 igneous textures? Felsic lavas are low temperature lavas because lower temperatures are required to keep felsic minerals molten (and if it was hotter it would have incorporated more iron and magnesium in comparison to silica). This article was most recently revised and updated by, https://www.britannica.com/science/felsic-rock. Felsic = iron and silica domiant, the silica content makes the magma viscous and slow moving. Log in Sign up. Since igneous rocks are characterised by silica content in them, mafic is the one with less silica content (approx. [citation needed] That usage, with the contrasting term "basic rock", was based on an incorrect idea, dating from the 19th century, that "silicic acid" was the chief form of silicon occurring in rocks. 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. Thousands of new, high-quality pictures added every day. Typical felsic rocks are dacite and rhyolite. Andesitic Magma. Intermediate rocks, such as andesite, fall between the mafic and felsic classifications. The similarity of the resulting term felsic to the German felsig, "rocky" (from Fels, "rock"), is purely[citation needed] accidental. Light-colored igneous rocks are more granitic (felsic) in composition and contain more feldspar and silica. STUDY. As the temperature drops within a magma diapir rising through the crust, some minerals will crystallize and settle to the bottom of the magma chamber, leaving the remaining melt depleted of those ions. Felsic minerals are usually light in color and have specific gravities less than 3.0. Although there are complete … Thick, viscous felsic magma can trap gas bubbles in a volcano’s magma chamber. The term “felsic” refers to the high content of quartz laden feldspar minerals in the lava. Obsidian is a natural glass - it lacks crystals, and therefore lacks minerals. Q. Felsic, mafic, intermediate, and ultramafic are classifications of the _____ of an igneous rock. Felsic magmas are higher in silica and contain lighter colored minerals such as quartz and orthoclase feldspar. Find Rhyolite Igneous Volcanic Rock Felsic Silicarich stock images in HD and millions of other royalty-free stock photos, illustrations and vectors in the Shutterstock collection. 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