What is the Earth made of?

Answer 1

Earth has a core of solid and liquid iron, a mantle of ultramafic rock, a crust of complex mineral compounds, and an atmosphere of nitrogen, oxygen, and other gases. Physical and chemical reactions on the Earth include the compound water (dihydrogen oxide or oxidane) in all three of its physical phases. Carbon-cycle (living) organisms utilize and alter the surface of the planet.

More detail is provided below:

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CrustEarth's crust is separated into two main types, oceanic crust and continental crust. They have differing chemical and physical properties and also differ significantly in thickness.

Oceanic Crust

Oceanic crust is typically enriched in the elements iron and magnesium and has less aluminum than the continental crust. It may broadly be described as having a basaltic composition. This means that it predominantly contains the minerals calcium feldspars (such as Anorthite), Pyroxene and Olivine.

Basalt generally has the following composition:

SiO2 - 45-52 %

Al2O3 - 14 %

FeO - 5-14 %

MgO - 5-12 %

CaO - 10%

Alkalis - 2-5 %

TiO2 - 0.5-2 %

Continental Crust

Continental crust is generally thicker and less dense than oceanic crust and tends to have a higher concentration of silica, aluminum and potassium, forming minerals such as quartz, potassium (or alkali) feldspars and muscovite mica.

The contintal crust is composed of a wide variaty of rock types from heavily metamorphosed and very ancient (>3Ga) cratonic and basement rocks to very young recently deposited sediments or recently erupted extrusive igneous rocks.

Continental crust tends to have the following average composition:

SiO2 - 57-58 %

Al2O3 - 16 %

FeO - 6-9 %

MgO - 4-5 %

CaO - 6-7%

Na2O - 3 %

K2O - 1-2 %

TiO2 - 0.7-0.8 %

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MantleThe Earth's mantle is composed of rocks that have higher concentrations of mafic minerals (containing iron and magnesium) and lower in concentrations of the felsic minerals (aluminum and silica) than the rocks of Earth's crust.

The concentrations of the above elements therefore mean that the Earth's mantle is composed of a series of minerals that are predominately calcium / iron / magnesium aluminum silicates.

Such as:

• Olivine - (Mg,Fe)2SiO4
• Pyroxene - X(Si,Al)2O6, where X represents either calcium, sodium, iron or magnesium
• Spinel - MgAl2O4
• Garnet - X3Y2(SiO4)3 where X and Y can be a mixture of aluminum, iron, calcium, manganese or magnesium.

At depths shallower than approximately 460 km, these minerals form the rocks types Peridotite, Dunite (Olivine-rich Peridotite), and Eclogite.

At depths greater than 410 km Olivine becomes unstable and is replaced by a number of different mineral forms known as poly-morphs which are stable at higher pressures. These include Wadsleyite which forms at depths between 410 and 520 km and Ringwoodite which forms between 520 and 600 km deep.

These depths are based on a number of seismic dicontinuities at the depths of 410 km (thought to mark the transition from Olivine to Wadsleyite) and at 520 km (thought to mark the transition from Wadsleyite to Ringwoodite) respectively.

At depths greater than around 650 km these upper mantle minerals start to become unstable due to the increased pressure and the minerals below this take the structure of the minerals Perovskite and Ferropericlase although with differing chemical compositions and it is this seismic discontinuity at 650 km depth that marks the transition to the lower mantle.

Average mantle composition:

SiO2 - 45-48 %

Al2O3 - 3-4 %

FeO - 7-8 %

MgO - 37-39 %

CaO - 3 %

Na2O - 0.3-0.5 %

K2O - 0.03-0.12 %

TiO2 - 0.1-0.2 %

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Outer coreThe Earth's outer core is composed of molten iron and nickel.

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Inner CoreThe Earth's inner core is believed to be composed of a solid iron-nickel alloy.

Answer 2

Each of the layers of the earth is made of different substances. They include iron, oxygen, silicon, magnesium, sulfur, nickel, calcium, aluminum, silica, and an iron-nickel alloy.

Answer 3

The earth is made of rick