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What two factors determine the composition of an igneous rock?

What two factors determine the composition of an igneous rock?

Overview

  • Magma cools to form igneous rocks.
  • Two factors determine what type of rock forms.
  • The composition of the magma determines if the rock is mafic, felsic, or intermediate.
  • The rate of cooling determines the texture of the rock.
  • Many mountain ranges are made of granite.

What does the composition of igneous rock depend on?

The minerals present in a rock and their relative proportions in the rock depend largely on the chemical composition of the magma. This works well as a classification scheme if all of the minerals that could potentially crystallize from the magma have done so – usually the case for slowly cooled plutonic igneous rocks.

What factors affect the type of igneous rock?

The type of igneous rocks that form from magma is a function of three factors: the chemical composition of the magma; temperature of solidification; and the rate of cooling which influences the crystallization process.

What determines mineral and grain sizes of the rocks?

Texture relates to how large the individual mineral grains are in the final, solid rock. In most cases, the resulting grain size depends on how quickly the magma cooled. In general, the slower the cooling, the larger the crystals in the final rock.

How many minerals are common in igneous rocks?

About 200 minerals make up the bulk of most rocks. The feldspar mineral family is the most abundant. Quartz, calcite, and clay minerals are also common. Some minerals are more common in igneous rock (formed under extreme heat and pressure), such as olivine, feldspars, pyroxenes, and micas.

What three factors influence the texture of an igneous rock?

The three factors that influence the textures of igneous rocks are the speed of cooling, the silicate content, and the water content. The speed of cooling affects the texture because the faster the rate of cooling, the smoother the rock will be (finer texture, aphanitic).

What determines grain size of igneous rock?

How are the composition and texture of igneous rocks determined?

Many different types of igneous rocks can be produced. The key factors to use in determining which rock you have are the rock’s texture and composition. Texture relates to how large the individual mineral grains are in the final, solid rock. In most cases, the resulting grain size depends on how quickly the magma cooled.

What makes up the mineral composition of magma?

Solidification from magma produces great diversity in the mineral compositions which make up the rocks. There are general catagories which are keyed to the amounts of light and dark silicates in the rocks. At the light-colored extreme are rocks made up mainly of quartz and the feldspars, with about 70% silica.

Can a rock not be an igneous rock?

You tell me that the mineral assemblages on the chart are those found in igneous rocks and that if a rock doesn’t have one of those assemblages, then it’s not an igneous rock! But you also say that having one of those mineral assemblages is no guarantee that a rock is igneous!!

Which is the most abundant element in igneous rocks?

Most are composed of the eight most abundant elements in the Earth’s crust. Because of the dominance of oxygen and silicon in the crust, igneous rocks are mostly made up of silicate minerals.

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