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Examples Of Sedimentary Rock

Examples of Clastic Sedimentary Rocks

Conglomerate

conglomerateis made up of rounded pebbles cemented together. The pebbles have been rounded by the action of moving water. This could be from a river or stream or from waves on a long ago beach.

Because they have been transported by water the pebbles may be from a wide variety of rock types. The size of these rock fragments is over 2 mm in diameter.

After the pebbles have been deposited they are compacted by the sediments that pile up on top of them. Over very long periods of time the pebbles become cemented together by minerals. Silica, calcite, and iron oxides are the most common cementing minerals.

The rounded rock particles in the conglomerate are easily visible to the naked eye.

Conglomerateis made up of rounded pebbles cemented together. The pebbles have been rounded by the action of moving water. This could be from a river or stream or from waves on a long ago beach.

 

Because

6jasper-mookite-australian-mines3232they have been transported by water the pebbles may be from a wide variety of rock types. The size of these rock fragments is over 2 mm in diameter.

 

After the pebbles have been deposited they are compacted by the sediments that pile up on top of them. Over very long periods of time the pebbles become cemented together by minerals. Silica, calcite, and iron oxides are the most common cementing minerals.

 

The rounded rock particles in the conglomerate are easily visible to the naked eye.


Sandstone

sandstone-argillaceousis as its name says sand grains cemented together into solid stone. The grain size of sandstone is 1/16 to 2 mm in diameter.
Sandstone is made up mostly of quartz. There are two reasons for this. First quartz is one of the most abundant minerals on earth. Second is that quartz is very durable. It resists weathering and chemical change.
Silica, calcite, and iron oxides are the most common cementing minerals for sand stone.

These minerals are deposited in the spaces between the sand grains by water.
Over the course of thousands or even millions of years the minerals fill up all of the spaces.
When iron is present in the cementing minerals the sandstone takes on a reddish color.


Silt stone

siltstoneis made from silt of course. Silt is another name for clay and is very fine grained. The grain size is from 1/16 to 1/256 of a millimeter in diameter. It is very similar to sandstone in appearance but with a finer texture.
Once deposited the silt becomes compacted and cemented together into solid stone.
Silica, calcite, and iron oxides are the most common cementing minerals for siltstone. These minerals are deposited in the spaces between the silt grains by water. Over the course of thousands or even millions of years the minerals fill up all of the spaces resulting in solid rock.



Shale

shale is similar to siltstone but with even finer grain size, less than 1/256 of a millimeter in diameter.
It is a very common sedimentary rock.
It is composed of silt or clay.

This is very fine particles of weathered and deconposed rock.
Once deposited the silt becomes compacted and cemented together into solid stone.
Silica, calcite, and iron oxides are the most common cementing minerals for shale.

These minerals are deposited in the spaces between the silt grains by water.
Over the course of thousands or even millions of years the minerals fill up all of the spaces. Shale is usually found in layers.


Examples of Chemical Sedimentary Rocks

Evaporates

Halite

halite1is also known as rock salt. The chemical name is sodium chloride NaCl It is called an evaporate.

It forms in places where sea water has been isolated from the ocean forming a lake.

As the saltwater evaporates in the lake the salt becomes concentrated in the remaining water.

As the water continues to evaporate the lake can no longer hold the same amount of salt.

The salt precipitates out and is deposited as crystallized sodium chloride or salt.



Gypsum

gypsumis an evaporate made of calcium sulfate that has many forms.

Clear flattened crystals are called selenite.

Satin spar and alabaster are also common forms of gypsum.




Carbonates

Limestone

limestoneis made primarily of calcium carbonate or calcite.

The most common source of this calcite is the shells of marine organisms.







Fossiliferous Limestone

fossilis limestone that contains the remains of ancient plants or animals in the form of fossils.








Siliceous Rocks

Chert

chertis a micro crystalline sedimentary rock that is silica rich. It has many forms and colors.








Organic Sedimentary Rocks

Coal

coalis composed of organic matter in the form of plant fragments. Coal can be:
* Lignite is black and has a crumbly consistency.
* Bituminous coal can be dull to shiny and black.
* Anthacite is usually considered metamorphic


Organic Sedimentary Rocks

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