Start studying Intrusive or Extrusive/Mafic or Felsic. Rhyolite. Felsic, intermediate and mafic igneous rocks differ in their mineral composition. Rhyolite Felsic lava 800°-1000°C Lower temp and higher silica = more viscous. It is a glassy-textured, extrusive igneous rock. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Fine Grain. The mineral compositions of igneous rocks are usually described as being felsic, intermediate, mafic, or ultramafic (as examples, see Figure 4.7 and Figure 4.8). Andesite. Additionally, they contain somewhat more gas than do the ultramafic magmas, but not nearly so much as the felsic magmas. Intermediate. The rhyolite cooled rapidly, and the granite cooled slowly. Felsic rocks are made of light-colored, low-density minerals such as quartz and feldspar. 1. determine texture: coarse-grained (visible crystals) = plutonic, fine-grained (microscopic crystals), or porphyritic (visible crystals in fine groundmass) = volcanic. Instead rhyolite tuff and ash falls are more common. 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. If this were a list based on types of magma based on silica content, then felsic magma would sit at the top with 65% and 70%. Mafic and Felsic: Igneous rocks and the magma they come from can be classified as mafic and felsic based on their mineral content. So far so good, but what about the rhyolite and gabbro? "Mafic" is a term that describes igneous rocks or silicate material characterized by a rich content of iron and magnesium while felsic rocks are igneous rocks that are rich in light elements such as oxygen, aluminum, silicon, potassium, and sodium. Mafic rocks are darker and are composed of magnesium and iron. Rhyolite, extrusive igneous rock that is the volcanic equivalent of granite. Felsic rocks are rich in silica, potassium, sodium, and aluminum and contain only small amounts of iron, magnesium, and calcium. Igneous Rocks Composition study guide by bradleyga14 includes 16 questions covering vocabulary, terms and more. There is one important exception to the dark = mafic rule, and that is aphanitic, vesicle-free, black or very dark-gray glass that is called obsidian. In comparison with mafic rocks, felsic rocks are much lighter and as a result “float” higher in the lithosphere then mafic rocks. Felsic rocks, in general, form the bulk of the continental plates, while mafic basalt forms the seafloor. ANDESITIC ROCKS or Intermediate Rocks ANDESITE is a medium gray, fine-grained rock of volcanic origin, named after the Andes Mountains, but is abundant in all volcanic regions associated with subduction zones (where crust is sinking and partially remelting - example: volcanos associated with … Types of Lava. Rhyolite is an extrusive igneous rock, formed from magma rich in silica that is extruded from a vent to cool quickly on the surface rather than slowly in the subsurface. [1] 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. Intermediate Magma. Intermediate rocks are composed of the minerals amphibole and feldspar and contain a combination of light and dark minerals. Types of Basalt Mafic Magma Flood Pahoehoe Aa Pillow. The high silica content and lower temperatures of rhyolite magma result in high viscosities and violent eruptive styles. Rhyolite is an extrusive felsic (silicic) volcanic rock. Light-colored Rhyolite Formation and Location of Mafic Rocks. Felsic or Sialic Magma. Why not complete the set of stone variants with rhyolite, which is extrusive felsic, gabbro, which is intrusive mafic, and basalt, which is extrusive mafic? In the simplified classification, the intermediate (intermediate toned) aphanitic, crystalline igneous rock is andesite. sticky, hence … In column 2, indicate whether the rock is mafic, felsic, or intermediate. Obsidian has a very high SiO 2 percent. Well, as you can see, mankind is very good when a need arises to make simple concepts difficult to understand. Hence, rhyolite and basalt as fine-grained volcanic rocks are porphyritic and granite, syenite, etc. Mafic Magma. A common mafic rock is basalt. In certain cases where the granite forms very slowly, crystals can be up to several feet long. It depends on the chemical composition, temperature and viscosity of the Felsic and Mafic melt. Ultramafic. Igneous Rocks. RHYOLITE - aphanitic (small crystals) of felsic minerals with the same composition of granite. Igneous rocks are classified according to their mineral content: Ultramafic rocks are dominated by olivine and/or pyroxene. The mafic magmas are somewhat more viscous than the ultramafic magmas, but they are still fairly fluid. Felsic rocks are usually light in color and have specific gravities less than 3. Mafic. Igneous rocks are those that crystallize from magma, or liquid rock. Felsic Magma (Rhyolitic). All igneous rocks are formed by crystals that form as the molten material cools. Gabbro is the name given to intrusive mafic rocks, whereas basalt is the name given to extrusive mafic rocks. ; Mafic rocks are dominated by plagioclase and pyroxene (even if you can't see them with the naked eye) and smaller amounts of olivine. Obsidian is a natural glass - it lacks crystals, and therefore lacks minerals. These are the terms you needed to know for the pre-lab quiz. PART 1: Fill in the following table from the 6 common rocks we talked about in class: Like rhyolite, granite is a felsic rock, and is composed almost entirely of feldspar and quartz. felsic rock, highest content of silicon, with predominance of quartz, alkali feldspar and/or feldspathoids: the felsic minerals; these rocks (e.G., granite, rhyolite) are usually light coloured, and feature low density. Most rhyolites are porphyritic, indicating that crystallization began prior to extrusion. The first pair is two rocks that formed from a felsic magma. Basalt. lighter and darker shades. Types of Lava. 2. determine color/composition: mostly light minerals = felsic; half light, half black (or gray in fine grained rocks) = intermediate; mostly black minerals = mafic; mostly olivine = ultramafic 4.Mafic lava creates basalt while felsic lava produces andesitic and rhyolite rocks. Is Basalt felsic? as coarse-grained plutonic rocks are porphyraceous. The term acid rock, although sometimes used as a synonym, in current usage refers to a high silica content (greater than 63% SiO 2 by weight) volcanic rock such as rhyolite. Granite and rhyolite are considered felsic, while basalt and gabbro are mafic (click here for more information on mafic and felsic). Mafic rocks are made of dark-colored, higher-density minerals such as olivine and pyroxene. In their study, mafic group B inclusions and, to a lesser extent, group A are stated to be compatible with mafic components of andesite–dacite–rhyolite (ADR) arc-type suites (Whalen et al., 2002, p. 1560) with the stated implications about their petrogenesis under conditions of low pressure, dry melting, and fluxing by hydrous fluids derived from subducted lithosphere. Felsic magmas are the most viscous because of their high silica content. True or False: Rhyolite and Granite can both have the same mineral composition despite having two different appearances. On the opposite side of the rock spectrum are the iron and magnesium rich mafic and ultramafic minerals and rocks. RHYOLITE. 6.Mafic rocks are darker in color than felsic rocks. Andesitic Intermediate between basalt and rhyolite. Phenocrysts that make up porphyry should be felsic (quartz, feldspar). Rhyolite, andesite, and basalt form a series that varies in composition, from felsic to mafic because of an increasing fraction of iron+magnesium rich minerals that darkens the tone. Since the surface of the earth is covered by oceanic and continental crustal materials, granite and basalt are very common. Texture: aphanitic The color of … This is why continental rocks are felsic and oceanic rocks are mafic. In geology, felsic is an adjective describing igneous rocks that are relatively rich in elements that form feldspar and quartz. 5.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. Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.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. Crystallization may sometimes have begun while the magma was deeply buried; in such cases, the rock may consist principally of well-developed, large, single crystals ( phenocrysts ) at the time of extrusion. Felsic rocks are light in color and are composed of feldspars and silicates. In geology, felsic is an adjective describing igneous rocks that are relatively rich in elements that form feldspar and quartz. The second pair is two rocks that formed from mafic magma. The most common felsic rock is granite. Mineralogic contents – felsic versus mafic. Obsidian is an easily recognizable igneous rock. But unlike rhyolite, granite is rough textured and has obvious crystals. Felsic minerals tend to be white, pink and clear (transparent) in color, and hence these rocks will be a lighter overall color, while mafic minerals tend to be dark black, dark red, or dark green colors, and these mafic rocks will be a darker color, often black. * Felsic Classification of Igneous Rocks Intermediate Mafic Obsidian Basaltic glass Extrusive Ultramafic Texture Glassy (non-crystalline) Fine-grained Rhyolite Andesite Basalt Granite Diorite Gabbro Perl. It is also rich in feldspar and silica.. Because of its high silica content, felsic magma is viscous, i.e. Mafic and felsic can only be used to describe igneous rocks. These types of rocks are generally light colors as well. Quizlet flashcards, activities and games help you improve your grades. The basalt cooled rapidly, and the gabbro cooled slowly. 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