What is is an igneous rock?

Answer 1

An igneous rock is one formed from the cooling and solidification of magma or lava. Examples include basalt, rhyolite, pumice, scoria, granite, diorite, gabbro, and obsidian. Magma solidifying under the surface results in coarser grained intrusive igneous rock. Lava solidifying at or near the surface results in finer grained extrusive igneous rock.

Intrusive Rocks

Intrusive rocks are characterized by large crystal that forms deep underground.

Extrusive Rocks

They are characterized by fine-grained textures because their rapid cooling at or near the surface.

What do intrusive rock have in common with extrusive rocks? Igneous rocks which form by the crystallization of magma.

What is intrusive igneous rock?Intrusive igneous rock is formed from solidified magma below the surface of the Earth. Intrusive rock exhibits a phaneritic texture, where the individual crystal grains are visible without magnification. Examples of intrusive igneous rocks are granite, diorite, and gabbro.

Where do we find magma? In Laccolith, sills, radial dikes, sheets dikes, ring dike, and in pipes.

What is extrusive (volcanic) rocks?The main effect of extrusion is that the magma can cool much more quickly in the open air or under seawater, and there is little time for the growth of crystals.

What is an intrusive (plutonic) rock? The mineral crystals within them are large enough to see without a microscope.

What is the definition of an igneous rock? Igneous rock may form with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.

Where do we find ultramafic rocks?derived from the Earth's mantle. Ultramafic rocks are dark, heavy, and rich in iron and magnesium minerals.

Where do we find mafic rocks? Pertaining to rocks rich in dark, ferromagnesian minerals.

Where do we find intermediate rocks? Intermediate rocks contain roughly equal amounts of dark- and light-colored minerals. Igneous rock containing 56-65 percent silica.

Where do we find felsic rocks? Igneous rocks that are relatively rich in elements that form feldspar and quartz.

What is the difference between magma and lava? Magma is molten rock that exists below the surface of the planet. Lava is molten rock that has reached the surface of the planet Earth.

What is the similar between magma and lava? They're are both molten rock, also contain suspended crystals, dissolved gas.

How do we classify igneous rocks?chemical content and grain size.

Chemical content is the minerals that the igneous rock is made of. There are 4 main groups that igneous rock is divided into by chemical content. These are felsic, intermediate, mafic and ultramafic. Felsic rocks are those that are rich in silica content and low in iron and magnesium. Examples include obsidian, granite and rhyolite. Mafic rocks are those low in silica and high in iron and magnesium. Examples include basalt, scoria and gabbro. Intermediate rocks have qulaities of both felsic and mafic rocks, examples include andesite and diorite. And Ultramafic rocks are those that are very high in iron and magnesium and very low in silica, examples include kimberlite, dunite and periodotite.

grain size is the size of the interlocking crystals that form the igneous rock. These crystals can be as large as a person to microscopic in size. In fact, some igneous rocks have no crystals at all and are called glass. What determines grain size is the amount of time a rock has to cool before it solidifies. Rocks that have more time to cool produce larger crystals and rocks with very little time to cool produce smaller crystals. Glasses have almost no time to cool at all.

The largest grain size goes to pegmatite which often has crystals a few inches across, but in rare cases, the crystals can be measured in feet.

other rocks with large rains are granite, gabbro and diorite

small grain size rocks include rhylote and basalt

and glasses include obsidian and pumice

some igneous rocks have crystals of different sizes. these rocks are called porphory. They are different sizes because the minerals in the rock have different freezing points. Those with higher freezing points have more time to solidify and will produce larger crystals.

What is the difference between intrusive and extrusive igneous rock? Both are formed from the crystallization of minerals caused by the cooling of magma.

Intrusive igneous rocks cooled below the surface of the planet, however, and generally display larger crystals due to the increased amount of time spent at mineral crystallization temperatures from the insulating effect of surrounding material.

Examples: granite, gabbro, diorite, peridotite.

Extrusive rocks are formed from magma at or above the surface of the planet, and generally display smaller mineral crystals, or no crystals at all, because of the rapid cooling environment in which they form. Chemically, an intrusive and extrusive rock could be identical, the only difference being the size of the mineral crystals they contain.

Examples: obsidian, rhyolite, pumice, scoria, basalt.

Intrusive Rocks

Igneous rocks which form by the crystallization of magma at a depth within the Earth are called intrusive rocks. Intrusive rocks are characterized by large crystal sizes, i.e., their visual appearance shows individual crystals interlocked together to form the rock mass. The cooling of magma deep in the Earth is typically much slower than the cooling process at the surface, so larger crystals can grow. Rocks with visible crystals of roughly the same size are said to have a phaneritic texture.

Extrusive Rocks

Igneous rocks which form by the crystallization of magma at the surface of the Earth are called extrusive rocks. They are characterized by fine-grained textures because their rapid cooling at or near the surface did not provide enough time for large crystals to grow. Rocks with this fine-grained texture are called aphanitic rocks. The most common extrusive rock is basalt.

What can texture tell us about the history of the rock and melt? The initial composition of the magma is dictated by the composition of the source rock and the degree of partial melting.

How is magma formed? It is formed when hot (very hot) rocks experience a drop in surrounding pressure, or when subducted wet lithosphere is introduced into the mantle. When it "breaks out" onto the surface of the earth, we call it lava.

What is Partial melting? The process in which different minerals melt into magma at differenttemperatures, changing itscomposition.

How does magma evolve? Where magma erupts on the surface of the earth, temperatures are lower and cooling of the magma takes place much more rapidly. This is the extrusive or volcanic environment and results in extrusive or volcanic igneous rocks.

How does magma differentiate? processes that operate during transportation toward the surface or during storage in the crust can alter the chemical composition of the magma. These processes are referred to asmagmatic differentiation and include assimilation, mixing, and fractional crystallization.

How does magma fractional crystallization? Fractional crystallization (fractionation) is that process of magmatic differentiation that accompanies the failure of early-forming crystals to react to the melt that remains. The process of fractional crystallization is responsible for the bulk of differentiation that is occurs in igneous rocks.

HOW does composition layering occur in igneous bodies? A layered intrusion is a large sill-like body of igneous rock which exhibits vertical layering or differences in composition and texture.

What is Bowen's reaction series? Bowen's Reaction scale lists the order in which minerals crystallize. Olivine or ultramafic minerals are the first to crystallize. They do so at high temperatures, whereas quartz is the last to crystallize, and at low temperatures. Through Bowen's many studies, he found that the order of magma from high to low temperature is ultramafic, mafic, intermediate, and felsic. Plagioclase feldspar follows the crystallization of olivine.

What is Bowen's reaction series about? The Bowen Reaction Series is a chemical model that helps us to understand the origin and variety of igneous rocks that we find spread around the Earth.