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3. Limestone: It is mainly made of minerals of calcium (calcium Limestone
carbonate). Some of it is formed from sea shells, corals and Shale
bones of animals. It is used to make bricks and glass. It is also
used to make quick lime, chalk and cement.
4. Shale: It is formed from clay and mud deposited in river beds.
Shale is grey in colour. It is made of parallel layers which
readily split into flat pieces. It is used to make tiles and bricks.
It is also mixed with limestone to make cement.
5. Dolomite: It is mainly made of magnesium. Like limestone, it
can be used in the manufacture of cement and also to extract
magnesium.

Metamorphic Rocks Dolomite

Marble Metamorphic rocks are the third type of rocks. They formed
Slate from other rocks that are changed because of heat or pressure.
Earth movements can cause rocks to be deeply buried or
Quartzite squeezed. As a result, the rocks are heated and put under great
Gneiss pressure. They do not melt, but the minerals they contain are
changed chemically, forming metamorphic rocks. Quartzite,
marble, slate and gneiss are some examples of this rock.
1.Marble: Marble is pure and hardened limestone. It is hard,
smooth and crystalline. It is a precious building material which
is generally white in colour.
2.Slate: It is hardened shale. It is formed of smooth, black and
hard stone in fine layers. It splits easily into thin layers. It is
used as tiles for roofing and also for blackboards, slates and
flooring.
3.Quartzite: Hardened sandstone is called quartzite. As it is too
hard, it cannot be used as building material but to make
statues.
4.Gneiss: It is a metamorphic rock of granite. It has light and
dark bands like streaks. Polished gneiss can be used as tiles for
flooring.

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