Ring in the new year with a Britannica Membership, This article was most recently revised and updated by, https://www.britannica.com/science/pegmatite, Victoria and Albert Museum - Classical Ballet, College of Natural Resources - Pegmatites. Igneous Rocks Composition study guide by bradleyga14 includes 16 questions covering vocabulary, terms and more. GEOL A105L Igneous Rock Identification Lab Name: Dexter Doan Terms to know prior to completing this lab: intrusive, extrusive, plutonic, volcanic, texture, composition, mafic, felsic, intermediate, aphanitic, phaneritic, vesicular, porphyritic, pegmatitic, glassy. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Both Granite and diorite igneous rocks used as building materials. The name pegmatite has nothing to do with the mineral composition of the rock. Gabbro is the name given to intrusive mafic rocks, whereas basalt is the name given to extrusive mafic rocks. A dominant component of oceanic crust, basalt is the most abundant volcanic rock. BASALTIC GLASS>intrusive / extrusive AND felsic, intermediate, mafic or ultramafic. This is because of the difficulty in counting and sampling mineral grains in a rock which may have crystals from centimeters to meters across. DIORITE - phaneritic rock (large crystals) of both mafic and felsic minerals. Let us know if you have suggestions to improve this article (requires login). Click card to see definition . ... (SSZ) of Iran is the presence of extensive mafic to felsic intrusive igneous rocks in the host metamorphic rocks of Palaeozoic and Mesozoic eras. Similarly, crystal texture and form within pegmatitic rock may be taken to extreme size and perfection. Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. While difficult to be certain of derivation of pegmatite in the strictest sense, often pegmatites are referred to as "metamorphic", "granitic" or "metasomatic", based on the interpretations of the investigating geologist. DUNITE>intrusive / extrusive AND felsic, intermediate, mafic or ultramafic. Pegmatites are little different from the common igneous rocks in major elements of bulk composition, and they range from felsic to mafic (silica-rich to silica … Granite is a great example of Felsic rocks and muscovite, quartz, and some feldspar are the best examples of Felsic minerals. Next are so-called "Christmas tree" structures found as meter-scale, layer-parallel, dendritic concentrations of mafic or felsic minerals. Intruding the BUC, and in places gradational to the gabbros, is a suite of predominantly mafic, hornblende-bearing pegmatite dykes, which are the main focus of this study. PEGMATITE > intrusive / extrusive AND felsic, intermediate, mafic or ultramafic. Additionally, they contain somewhat more gas than do the ultramafic magmas, but not nearly so much as the felsic magmas. (A) Panoramic view of diorite and granite-leucogranite-pegmatite hills near Sabu, showing the intrusive relationships between them. The line in the pegmatite on the left indicates that the pegmatite is felsic, whereas the line in the pegmatite on the right indicates that the granite is intermediate O … [6] The primary source for caesium is pollucite, a mineral from a zoned pegmatite. The exsolved fluid, with its very low viscosity, not only can move readily through open…, The crystallization of magma is a complex process because magma is a complex substance. The word "felsic" is a term used in geology to refer to silicate minerals, magma, and igneous rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.They are usually light in colour and have specific gravities less than 3. Intermediate compositions lie between these two end members. 2. Is the mantle mafic or felsic? The term combines the words "feldspar" and "silica." Economic lode concentrations generally occur in zoned pegmatite bodies (i.e., those within which two or more different rock types are systematically disposed). Tilted mid-Tertiary volcanic and sedimentary rocks are preserved above a brittle … a. texture / composition b. composition / texture ... c. have the same texture but one is mafic and the other is felsic d. have the same texture but are made up of different minerals Mafic magmas are usually produced at spreading centers, and represent material which is newly differentiated from the upper mantle. End-members such as phlogopite, annite and siderophyllite all belong to the group. Perthite feldspar within a pegmatite often shows gigantic perthitic texture visible to the naked eye. Felsic magma or lava is higher in viscosity than mafic magma/lava. (B) Diorite is dismembered as xenoliths and partially assimilated by the intruding granite-leucogranite-pegmatite system. Granitic and syenitic pegmatite deposits are the chief source of commercial feldspar, sheet mica, and beryllium, tantalum–niobium, and lithium minerals. Pegmatite bodies are usually of minor size compared to typical intrusive rock bodies. Granite pegmatite (scale = 1cm) And felsic rocks usually have alkalis compared to Fe/Mg in mafic rocks. Examples of intrusive igneous rocks are diabase, diorite, gabbro, granite, pegmatite, and peridotite. The term “pegmatite” was first used by a French mineralogist René Haüy, but he used this term as a … It is contrasted with mafic rocks, which are relatively richer in magnesium and iron. Is the Kimberlite rock defined as ultramafic rock or felsic rock? They are also darker in color and denser. These are sometimes called granite pegmatites to indicate their mineralogical composition. Water and fluxes generally reduce the melting point. Pegmatites associated with granitic domes within the Archaean Yilgarn Craton intruding ultramafic and mafic rocks contain red, orange and brown almandine garnet. Granite is the most common felsic … 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. It is however impossible to quantify the mineralogy of pegmatite in simple terms because of their varied mineralogy and difficulty in estimating the modal abundance of mineral species which are of only a trace amount. It is commonly erupted as passive lava flows due to its low viscosity (resulting from high magmatic temperatures and low silica contents). Pegmatites may be mined because of their high content of feldspars, clay (if weathered), mica, or many metal-bearing minerals. London, D. (2008): Pegmatites. The shape of pegmatite bodies range from from tabular to inverted teardrop-shaped and range in size from several tens of meters up to a kilometer or more in extent! DIORITE - phaneritic rock (large crystals) of both mafic and felsic minerals. For example, granite contains around 70% of silica. However, compositions such as gabbro pegmatite, syenite pegmatite, and any other plutonic rock name combine… Material moves about very easily in these wet melts, and crystals can grow very large in a short time. Common mafic rocks include basalt and gabbro. Mafic is an adjective describing a silicate mineral or igneous rock which is rich in magnesium and iron.The term is a portmanteau, made up from "magnesium" and "ferric".. Mafic minerals are usually dark in color and have a specific gravity greater than 3. As those which form granites, contain several percent water dissolved in defines... 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