why are there so many kinds of rocks

Why are there so many kinds of rocks?

What are minerals?

- They are natural, non-living substance that makes up the rocks

(1) Diamond:- It is a hard mineral.- It is used to cut steel & as jewelry.

Types of minerals

(2) Gold:- It is a shinny mineral.- It is used as jewelry.

(3) Graphite:- It is a dark, soft & dull mineral.- It is used in pencils for writing.

(4) Quartz:- It is used to make glass.

(5) Hematite:- It is used to make iron which is used

in building.

(6) Halite:- It is used to make salt for food.

(7) Copper:- It is used to make electrical wires.

1- Hardness:There is a scale

called: Moh’s scale that tells the hardness of the minerals.

How to identify minerals?

2- Color:It’s not the best

way to identify minerals as some minerals can have many colors like: Quartz.

(It can be pink, purple, blue, yellow & white)

3- Streak:It is the color of

the powder that a mineral leaves behind when you scratch it along a white tile.

4- Luster:It is the way light bounces off the surface

of the mineral.

(some minerals have metallic luster)

(Others have dull luster “not shinny”)

(Others have glassy luster)

They are natural solids which are made of one or more

minerals together.Example: Granite {Mixture of Mica + feldspar +

Quartz}

Rocks

Types of rocks

Igneous rocks Sedimentary rocksMetamorphic rocks

They are rocks that are formed when rocks come out of a volcano

“melted” & then cooled & hardened on earth’s surface.

If they are cooled quickly: rocks will look like glass (ex: Obsidian)

If they are cooled slowly: rocks will have large grains (ex: Granite)

Igneous rocks

Granite is used for building schools & houses.

Uses of Igneous rocks

(They are rocks that form from materials that has settled into layers)

The layers are squeezed together to form a rock.

Examples: Limestone Sandstone

Sedimentary rocks

How are sedimentary rocks formed?

- Wind & water break big rocks into bits & pieces, then the small pieces are carried by the wind or water and settle into layers & after a long time they become harden & form sedimentary rocks.

Limestone is used for making glass. Shale is used in making bricks , pottery &

china.

Limestone & shale are used in making cement.

Uses of sedimentary rocks

Temperature & pressure can change rocks from one type to another.

Metamorphic rocks are rocks that have been changed by temperature & pressure.

Example: Gneiss Marble

Metamorphic rocks

Slate is used for tiles of roofs & walk ways .

Marble is used to making monuments & statues.

Uses of Metamorphic rocks