is obsidian mafic felsic or intermediate

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What is the difference between mafic and felsic?

What is the difference between mafic and felsic minerals in rocks? Chemically, mafic rocks are enriched in iron, magnesium and calcium and typically dark in color. In contrast, the felsic rocks are typically light in color and enriched in aluminium and silicon along with potassium and sodium.

Is mafic always either ferromagnesian or felsic?

Mafic materials can also be described as ferromagnesian. Chemically, mafic rocks are enriched in iron, magnesium and calcium and typically dark in color. In contrast, the felsic rocks are typically light in color and enriched in aluminium and silicon along with potassium and sodium. The mafic rocks also typically have a higher density than ...

Is obsidian a rock or a mineral?

Obsidian is an igneous rock that is formed from the erupted lava of a volcano. Obsidian is made of felsic type material, rich in feldspar and quartz, which is high in silicate minerals. This formed rock is considered to be one of natures occurrences of natural glass. Obsidian is an extrusive igneous rock and not an intrusive rock.

Is obsidian intrusive or extrusive?

Obsidian is usually an extrusive rock - one that solidifies above Earth's surface. However, it can form in a variety of cooling environments: along the edges of a lava flow (extrusive) along the edges of a volcanic dome (extrusive) around the edges of a sill or a dike (intrusive) where lava contacts water (extrusive)

Is obsidian felsic or mafic or intermediate?

Though obsidian is usually dark in color similar to mafic rocks such as basalt, obsidian's composition is extremely felsic. Obsidian consists mainly of SiO2 (silicon dioxide), usually 70% or more.

Is obsidian a felsic rock?

This rock is called obsidian. It is an igneous rock and forms when felsic (rich in silica) lava cools quickly on the earth's surface—forming natural glass!

Why is obsidian considered felsic?

Obsidian is created when the volcano's felsic lava cools quickly with minimal crystal growth. The chemicals (hodium silica content) produce a elevated viscosity that shapes a natural glass from lava when rapidly drying.

Which igneous rock is felsic mafic and intermediate?

Igneous Rocks by CompositionCoarse-Grained TexturesFine-Grained TexturesPeridotite = UltramaficKomatiite (Ultramafic, but too rare to worry about at this point in your life)Gabbro = MaficBasalt = MaficDiorite = IntermediateAndesite = IntermediateGranite = FelsicRhyolite = Felsic

What type of rock is obsidian?

Rondi: Everyone, meet Obsidian , an igneous rock that from melted rock, or magma. Obsidian is an "extrusive” rock, which means it is made from magma that erupted out of a volcano. If it was an igneous rock that formed from magma underground and did not erupt, it would have been called an "intrusive" rock.

Is obsidian mafic or ultramafic?

Classification of Igneous RocksTEXTUREFelsicMaficPhaneriticGraniteGabbroAphaniticRhyoliteBasaltVesicularPumiceScoriaGlassyObsidian1 more row

What composition is obsidian?

obsidian, igneous rock occurring as a natural glass formed by the rapid cooling of viscous lava from volcanoes. Obsidian is extremely rich in silica (about 65 to 80 percent), is low in water, and has a chemical composition similar to rhyolite. Obsidian has a glassy lustre and is slightly harder than window glass.

What properties does obsidian have?

Obsidian is truth-enhancing. A strongly protective stone, it forms a shield against negativity. It blocks psychic attack and absorbs negative energies from the environment. Obsidian draws out mental stress and tension.

Is granite felsic or mafic?

felsicCompilations 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 ...

Which rock has an intermediate composition?

Intermediate is a composition between felsic and mafic. It usually contains roughly-equal amounts of light and dark minerals, including light grains of plagioclase feldspar and dark minerals like amphibole.

What type of rock is mafic?

mafic rock, in geology, igneous rock that is dominated by the silicates pyroxene, amphibole, olivine, and mica. These minerals are high in magnesium and ferric oxides, and their presence gives mafic rock its characteristic dark colour.

What two rock types are neither felsic nor mafic?

Igneous rocks composed of mostly plagioclase feldspars and amphibole (hornblende) are neither felsic nor mafic, but are called intermediate.

Why is obsidian black but felsic?

Obsidian is a natural glass - it lacks crystals, and therefore lacks minerals. Obsidian is typically black in color, but most obsidians have a felsic chemistry. Felsic igneous rocks are light-colored, so a felsic obsidian seems a paradox. Mafic obsidians are scarce, but they have the same appearance.

What composition is obsidian?

obsidian, igneous rock occurring as a natural glass formed by the rapid cooling of viscous lava from volcanoes. Obsidian is extremely rich in silica (about 65 to 80 percent), is low in water, and has a chemical composition similar to rhyolite. Obsidian has a glassy lustre and is slightly harder than window glass.

Is granite felsic or mafic?

felsicCompilations 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 ...

Is gabbro mafic or felsic?

Mafic Intrusive Igneous Rocks1 Mafic Intrusive Igneous Rocks. Gabbro is a mafic intrusive coarse-grained rock with allotriomorphic texture.

What is the difference between granite and rhyolite?

Granite is the name given to intrusive felsic rocks, whereas rhyolite is the name given to extrusive felsic rocks. Felsic rocks are produced primarily in convergent plate boundaries in which an oceanic plate is subducting beneath either another oceanic plate (such as in Japan) or a continental plate ...

What are felsic rocks made of?

Felsic rocks. Rocks composed mostly of biotite, muscovite, sodium-rich plagioclase feldspars, potassium feldspars, and quartz make up the felsic family of igneous rocks. Felsic magmas are much more viscous than the intermediate magmas. Additionally, felsic magmas may have very high gas contents.

Why is felsic magma the most violent?

However, because of its high gas content, when felsic magma does erupt, the eruption is the most violent. The explosive eruption often results in the emplacement of ashflow tuffs and volcanic breccias.

What is the dominant rock type of the upper mantle?

Peridotite appears to be the dominant rock type of the upper mantle. It is very rarely exposed at the surface. Chunks of peridotite, however, are often brought up by other magmas (of the mafic family- see below). These included chunks are called inclusions or xenoliths (meaning "foreign rock").

What is the most common type of glass in the cooling of felsic lavas?

In addition, the viscosity of the magma hinders crystal growth. Consequently, obsidian or volcanic glass is most common in the cooling of felsic lavas.

What is an ultramafic rock?

Ultramafic rocks are given names depending on whether they are intrusive or extrusive.

Why do mafic lava flows travel so far?

Because of their relatively low viscosity, mafic lavas may travel great distances and "flood" the landscapes over which they flow. Mafic lava flows are thin and sometimes called plateau or flood lavas. Volcanoes made up of mafic flows are typically shield volcanoes and/or cinder cones.

What type of rocks have biotite?

To be more specific, felsic rocks typically have biotite and/or amphibole; intermediate rocks have amphibole and, in some cases, pyroxene; and mafic rocks have pyroxene and, in some cases, olivine. Figure 4.3.1: A simplified classification diagram for igneous rocks based on their mineral compositions. [Image Description]

What are the silicates in the upper right?

silicates in the upper right (biotite, amphibole, pyroxene, and olivine). In classifying igneous rocks, the first thing to consider is the percentage of ferromagnesian silicates.

What is the difference between mafic and felsic rocks?

In general, the size of crystals is proportional to the rate of cooling.

What are the blue lines in Figure 4.3.2?

The dashed blue lines (labelled a, b, c, d) in Figure 4.3.2 represent four igneous rocks. Complete the table by estimating the mineral proportions (percent) of the four rocks (to the nearest 10%).

What type of rock forms when lava cools so rapidly that few, if any, crystals form?

Igneous rocks that form when lava cools so rapidly that few, if any, crystals form, are often glassy. Two common glassy rocks formed rapid cooling (or quenching) of lava are and . Pumice is typically light in colour owing to its felsic composition, and is distinguished by its frothy glassy texture and low density.

How does magma bubble?

As magma approaches the surface, the pressure exerted on it decreases , and gas bubbles start to form, much like once a bottle of pop has been opened. The more gas there is in the magma, the more bubbles form. If the magma is runny enough, the gases will rise up through it and escape to surface.

How big are igneous rocks?

Typically that means they are larger than about 0.5 millitmeres (mm) — the thickness of a strong line made with a ballpoint pen.

What are the minerals in felsic rocks?

Some felsic volcanic rocks contain phenocrysts of mafic minerals, such as hornblende, pyroxene, or a feldspar mineral, and must be named after the phenocryst mineral, such as 'hornblende-bearing felsite.'. The TAS diagram of Le Maitre is used to determine the chemical name of a felsic rock (1975).

What are the most common felsic minerals?

Quartz, muscovite mica, and orthoclase feldspars are common felsic minerals. Granite, the refined result of the earth's internal separation process, is the most common felsic rock. Felsic and mafic rocks are igneous rocks classified according to their silica content.

Why are ultramafic rocks darker than felsic rocks?

The dark color of the mafic is due to the coexistence of magnesium and iron, according to geologists.

What are the two terms used to describe the chemical composition of silicate minerals, magmas, and igneous rocks?

Mafic and Felsic Both are made-up terms used to indicate the chemical composition of silicate minerals, magmas, and igneous rocks.

Why are volcanic eruptions less violent?

The volcanic eruption would most likely be less violent than the Hawaiian Island volcanic eruptions due to the runnier lava.

What are the two terms used to describe rocks?

Two terms are widely used to describe the characteristics of rocks and lava in the concept of mineralogy, or geology in a wider context. The terms mafic and felsic are used to describe these types of rocks.

What is a mafic mineral?

Mafic refers to silicate crystals, magmas, and rocks with a high proportion of heavier elements. The name "mafic magma" comes from the combination of the letters MA and FIC, which stand for magnesium and iron in Latin. Mafic magmas are also high in calcium and sodium. Mafic minerals are usually dark in color with high specific gravities ...

What is the mineral called that has a low melting temperature?

Silicon dioxide, or silica, is a mineral most commonly known as quartz. Quartz has a relatively low melting temperature, so magma with a higher silica content can form at much cooler temperatures relative to magma that contains denser elements such as iron or magnesium.

What are the most fascinating phenomena on Earth?

Volcanoes are one of the most fascinating phenomena that grace Earth’s surface; they are the windows into the nether region, a brief glimpse into the underlying processes governing our world. A glimpse offered into the fiery subterranean processes that has inspired awe and fear throughout the span of the human race. Hawaiians worshiped volcano gods; Pliny the Younger reverently documented the destruction of Pompeii. Humankind has been diligently documenting and studying volcanoes for millennia in an attempts to understand volcanoes .

What type of lava forms basalt?

Mafic lava forms basalt and is associated with the lava flows seen on the Hawaiian Islands and similar shield volcanoes. The type of lava emitted in an eruption can reveal intimate details of the inner workings of not only the volcano, but also the underlying geological processes governing Earth’s surface.

What is the name of the lava flow that has the densest lava flows?

Mafic – 1832 – 2192 degrees Fahrenheit. “Mafic” is a term used to describe the densest lava flows. The word derives from a composite of the chemical symbols for Magnesium (Ma) and Iron (Fe). This magma has a low viscosity, which allows for gases to escape the volcano, and for the lava flows to erupt calmly and predictably.

What type of volcano is felsic magma?

In turn, felsic magma is associated with the volatile stratovolcano characterized by Plinian eruptions (mushroom cloud) followed by a deadly pyroclastic flow of hot ash, gas, and lava.

What is the temperature of felsic lava?

Felsic – 1202 – 1472 degrees Fahrenheit. The term “felsic” refers to the high content of quartz laden feldspar minerals in the lava. There are two types of felsic lava: rhyolite and dacite. These low temperature lava flows have a high viscosity, which clogs the inner workings of volcanoes trapping and compounding gases.

What is the name of the rock that has been liquefied due to the intense pressure and heat within the man?

Lava contained within the Earth’s crust is known as magma; rock that has been liquefied due to the intense pressure and heat within the mantle. Just as different solids such as ice or chocolate have different melting points, so do different rock types.

How do extrusive igneous rocks form?

Extrusive igneous rocks form when lava cools and hardens at the surface.

What is a dissolved gas in a melt that vaporizes at surface pressure?

3. Volatiles : dissolved gases in the melt that vaporize at surface pressure

Where is magma stored?

Magma is composed of molten rock and is stored in the Earth's crust.

Where are quartz and plagioclase found?

Plagioclase feldspar and quartz are minerals typically found in rocks with high silica content.

Is rhyolite felsic or morphic?

Granite and rhyolite are both felsic, but they differ in crystal size.

What is pumice rock?

PUMICE Pumice is a low-density, light-colored felsic volcanic rock. It commonly forms as a frothy upper surface on silicic lavas. SCORIA Scoria is a dark-colored extrusive volcanic rock with abundant large vesicles. It commonly forms as a bubble-rich upper surface on many basalt and andesite lavas.

What is the composition of Andesite?

ANDESITE Andesite is an extrusive volcanic rock with a composition that is intermediate between basalt and rhyolite. Andesite magma is characterized by intermediate temperatures and viscosities resulting in both passive (lava) and violent (pyroclastic) eruptive styles.

What is basalt volcanic rock?

BASALT Basalt is an extrusive mafic volcanic rock. It is commonly erupted as passive lava flows due to its low viscosity (resulting from high magmatic temperatures and low silica contents). A dominant component of oceanic crust, basalt is the most abundant volcanic rock. Other Characteristics: weathers to red-brown, hematite/limonite/clay mixture.

What is felsic enriched in?

Composition: felsic (silicic), enriched in silica and depleted in iron and magnesium

How is obsidian formed?

OBSIDIAN Obsidian is an extrusive volcanic rock formed by the rapid cooling of high viscosity magma. It is recognized by its glassy texture. Silicic magmatic compositions and fast cooling rates prevent the formation of crystals even at the microscopic scale.

Is rhyolite lava or lava?

The high silica content and lower temperatures of rhyolite magma result in high viscosities and violent eruptive styles. Rhyolite is rarely found as lava. Instead rhyolite tuff and ash falls are more common. Texture: aphanitic. Composition: felsic (silicic), enriched in silica and depleted in iron and magnesium.