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Structure of the Earth

We get many useful substances from rocks, such as building materials, metals and jewels. But where do we get the rocks themselves from?

The Earth’s crust is made out of rocks. The Earth’s crust is the thin outer layer of the Earth. It is about 30 km thick on land and only about 8 km thick under the sea.

crust

mantle

inner core

outer core

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Cross-section of the Earth

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What is the Earth’s crust made of?

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Minerals and metals

Many of the useful substances we get from the Earth’s crust are minerals, which can contain useful metals and other substances.

Here are the names and formulae of some common minerals:

Fe2O3

Al2O3

PbS

TiO2

Cu2S

haematite

bauxite

galena

chalcocite

rutile

mineral formula substance extracted from it

iron

aluminium

lead

titanium

copper

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Minerals and rocks

Minerals have a set chemical composition.

Rocks do not have a set composition and are often made up of several different minerals and other materials. For example, the rock granite is made up of the minerals quartz, feldspar and biotite.

Minerals are found in the Earth’s crust. Minerals that humans use are usually extracted from mines.

An area that has a lot of a specific mineral is called a deposit.

What is the difference between rocks and minerals?

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