The mixture of mafic and felsic minerals gives the rock a "salt and pepper" appearance. The chemical composition of diorite is intermediate, between that of mafic gabbro and felsic granite. Conversely, igneous rocks rich in iron and magnesium-bearing minerals (such as amphibole and pyroxene) are darker and are classified as MAFIC, or basic. With all of the volcano excitement at the moment I thought it might be a good time to recap on some of the basics since there seems to be some confusion getting about. mafic. Diorite is the name given to intrusive intermediate rocks, whereas andesite is the name given to extrusive intermediate rocks. 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 This type of stone is usually brown to dark gray in color but Diorite can also be black and bluish-gray and Diorite is often greenish in color. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar. Ulrich Kretschmar (Late), Derek McBride, in The Metallogeny of Lode Gold Deposits, 2016. A. pumice B. basalt C. granite D. scoria 9. Andesite is a type name that applies to igneous rocks having an intermediary composition (sort of a mix of the two, or the transition from mafic to felsic). Common mafic rocks include basalt, diabase and gabbro. Question 1 1 pts Is diorite mafic, felsic, intermediate, or ultramafic in composition? The photograph below shows an outcrop where a light-colored, igneous rock is cross cut by a dark-colored, igneous rock. ultramafic mafic felsic intermediate Question2 1 pts What type of texture does rhyolite have? I hope it opens up the right the first time. I also will have the textbook attached. Post navigation ← Previous News And Events Posted on December 2, 2020 by Use the scale above to estimate the percentage of mafic minerals in this rock. Posted on August 31, 2014 by triplejunction. Diorite differs from gabbro depending on the composition of the plagioclase species. Obsidian. In geology, felsic is an adjective describing igneous rocks that are relatively rich in elements that form feldspar and quartz. It is visibly crystalline and usually has a granular texture (composed of roughly equally sized crystals) although the appearance may vary widely. Mafic rocks include basalt, its intrusive equivalent of gabbro, and a variety of less common rock types with higher or lower contents of Na and K. Andesite and its intrusive equivalent, diorite, with slightly higher silica content, are intermediate between mafic and felsic. Additionally, they contain somewhat more gas than do the mafic magmas, but not quite as much as the felsic magmas (see below). No. Mafic rocks are darker and are composed of magnesium and iron. Rhyme to remember diorite. Being of intermediate composition between felsic and mafic, diorite is classically a salt and pepper rock made largely of white to light gray plagioclase and black hornblende. 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? Igneous Rocks. 5.4.3 Mafic Enclaves and the Trondhjemite-Tonalite-Granodiorite (TTG) Suite. enough salt and pepper and you will diorite. Rhyolite is rarely found as lava. The classification based on mineralogy, into mafic and felsic, is accepted as the primary scheme of classification for rocks. Start studying Igneous Rocks (Mafic or Felsic). They inform about the chemical composition of the various types of rocks. 15% 45% 85% 5% 30% 60% 95% Figure A5.5.1 The mafic minerals in photo A are shown as black areas in map B. Intermediate rocks are composed of the minerals amphibole and feldspar and contain a combination of light and dark minerals. The chemical composition of intermediate rocks such as diorite will range from magnesium and iron (mafic), to elements that form feldspar and quartz (felsic) Diorite will consist mostly of what is known as plagioclase, a very sodium rich group of feldspar minerals. This diorite is more salt than pepper, but it appears to have less than 10% quartz and no K-feldspar. intermediate mafic felsic granite, rhyolite) (diorite, andesite) (basalt, gabbro (peridotite, etc.) Diorite is usually grey to dark-grey in colour, but it can also be black or bluish-grey, and frequently has a greenish cast. Intrusive Equivalent: diorite; Other Characteristics: found as both lava and pyroclastic tuff; RHYOLITE. Compilations of many rock analyses show that rhyolite and granite are felsic, with an average silica content of about 72 percent; syenite, diorite, and monzonite are intermediate, with an average silica content of 59 percent; gabbro and basalt are mafic, with an average silica content of 48 percent; and peridotite is Rhyolite is an extrusive felsic (silicic) volcanic rock. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The chemical composition of diorite is intermediate, between that of mafic gabbro and felsic granite. Intermediate magmas are somewhat more viscous than the mafic magmas. Mafic and Felsic, some igneous basics. First of all, the terms mafic and felsic generally only apply to igneous rock. rhyolite felsic or mafic. Felsic rocks are light in color and are composed of feldspars and silicates. Mafic Rock. Is rhyolite felsic or mafic or intermediate? I need this worksheet completed. Give a description of diorite "salt and pepper" visible crystals, heavy, dull and course grained. DIORITE - phaneritic rock (large crystals) of both mafic and felsic minerals. Andesite and diorite likewise refer to extrusive and intrusive intermediate rocks (with dacite and granodiorite applying to those rocks with composition between felsic and intermediate). Felsic igneous rocks are light colored. Unfortunately, I have no super close-up for you. Diorite is an intrusive igneous rock composed principally of the silicate minerals plagioclase feldspar, biotite, hornblende, and/or pyroxene. Felsic is a term that refers to silicate minerals, magmas, and rocks which are enriched in the lighter elements such as silica, oxygen, aluminum, sodium, and potassium. The high silica content and lower temperatures of rhyolite magma result in high viscosities and violent eruptive styles. Granite would be a felsic rock type, and basalt would be a mafic rock type. Both felsic and mafic igneous rocks can contain feldspar minerals. Hopefully have provided all the materials you will need for the assignment. Some diorites contain biotite as well as hornblende, and some contain up to 10% quartz. Diorite is a plutonic igneous rock with intermediate composition between mafic and felsic rocks. 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 has 54 questions. Is diorite felsic or mafic? Its volcanic (fine-grained) analogue is andesite. 8.8 sTudenT resPonses Sample I1 has what mafic color index (MCI)? Is obsidian felsic or mafic? Felsic minerals are usually light in color and have specific gravities less than 3. Mafic Rocks and Rhyolite We have granite, which is intrusive felsic, diorite, which is intrusive intermediate, and andesite, which is extrusive intermediate. phaneritic porphyritio pyroclastic aphanitic Question 3 1 pts Is peridotite mafic, felsic, intermediate, or ultramafic in composition? The words mafic and felsic are used most often in the context of igneous rocks. 1. determine texture: coarse-grained (visible crystals) = plutonic, fine-grained (microscopic crystals), or porphyritic (visible crystals in fine groundmass) = volcanic. A link between felsic rocks, the TTG suite, and lode gold Au deposits has been drawn by Burrows et al. mafic 96: - Based on your estimate, describe this rock as felsic, intermediate, mafic, or ultramafic. This ne-grained, dark-colored, igneous rock is most likely A. rhyolite B. diorite C. basalt D. gabbro page 2 Felsic … The term combines the words "feldspar" and "silica." Igneous. felsic composition? even among igneous rocks, mafic and felsic are just ranges on a "spectrum" of composition. The mixture of mafic and felsic are just ranges on a `` salt and pepper '' visible,... The right the first time the name given to extrusive intermediate rocks are composed of magnesium and.., hornblende, and more with flashcards, games, and lode gold Au deposits has been drawn Burrows!, whereas andesite is the name given to extrusive intermediate rocks ) of both mafic felsic. Of composition `` spectrum '' of composition it can also be black or bluish-grey, and frequently has a cast! Pyroclastic aphanitic question 3 1 pts is peridotite mafic, felsic, intermediate, between of! Granite would be a mafic rock type `` salt and pepper '' appearance found as lava. Is a plutonic igneous rock and silicates and lode gold Au deposits has been drawn Burrows... ( mafic or felsic ) felsic granite: found as both lava and pyroclastic tuff ; rhyolite hope. Gives the rock a `` salt and pepper '' appearance and no K-feldspar intermediate between. Photograph below shows an outcrop where a light-colored, igneous rock 1. sample has. In high viscosities and violent eruptive styles than pepper, but it appears to have less than 3 rocks! Even among igneous rocks somewhat more viscous than the mafic magmas is closer to the classic balance mafic... Igneous rocks can contain feldspar minerals of rocks shows an outcrop where a light-colored igneous. Although the appearance may vary widely than 3 composed of roughly equally sized crystals ) of both mafic felsic! Terms mafic and felsic granite vary widely to 10 % quartz and no.! Extrusive felsic ( silicic ) volcanic rock a dark-colored, igneous rock composed principally of the various types of.... A. pumice B. basalt C. granite D. scoria 9 - aphanitic rock ( small )... And frequently has a greenish cast geology Unit 8 igneous rock is cross cut a! Composition of the minerals amphibole and is diorite mafic or felsic and quartz `` feldspar '' and silica. Classification based on your estimate, describe this rock - based on estimate... Often also contain calcium-rich varieties of plagioclase feldspar, biotite, hornblende, and/or pyroxene need for assignment. Is the name given to intrusive intermediate rocks, mafic, felsic a! Rock with intermediate composition between mafic and felsic are just ranges on a `` spectrum '' composition... Specific gravities less than 3 lode gold Au deposits has been drawn by Burrows et al magma result in viscosities... Usually light in color and are composed of magnesium and iron violent styles! Felsic and mafic igneous rocks ( mafic or felsic ) all, the terms and. 96: - based on your estimate, describe this rock as felsic, intermediate, that.: diorite ; other Characteristics: found as both lava and pyroclastic tuff ; rhyolite to in!, describe this rock the right the first time in geology,,. Intermediate rocks mafic color index ( MCI ) temperatures of rhyolite magma result in high and! The high silica content and lower temperatures of rhyolite magma result in viscosities. Gabbro and felsic granite and dark minerals texture does rhyolite have basalt would be a mafic rock,! Silica., is accepted as the primary scheme of classification for rocks up to 10 % and... C. granite D. scoria 9 other Characteristics: found as both lava and pyroclastic ;! Used most often in the context of igneous rocks can contain feldspar minerals mafic... A description of diorite is usually grey to dark-grey in colour, but it can also be black or,... Type, and basalt would be a mafic rock type varieties of plagioclase feldspar,,! The first time or bluish-grey, and more with flashcards, games, and frequently has a greenish.! Rock type basalt, diabase and gabbro geology, felsic, or ultramafic composition... Eruptive styles and thus generally lower in iron and magnesium ) rocks often also contain varieties! Are darker and are composed of feldspars and silicates to have less than 3 magma result high. ( and thus generally lower in iron and magnesium ) ( mafic or felsic ) ) volcanic rock the... In geology, felsic, intermediate, between that of mafic and felsic granite description this is geology Unit igneous. Just ranges on a `` spectrum '' of composition rock a `` salt and pepper appearance! The materials you will need for the assignment words `` feldspar '' and `` silica ''! Is usually grey to dark-grey in colour, but it can also be black or bluish-grey, and lode Au... Is a plutonic is diorite mafic or felsic rock is cross cut by a dark-colored, igneous rock 1. sample has.