Identification of

Minerals

Mr. Harper’s science mini lesson with audio 2011

Cookies are made from ingredients like flour, sugar, and chocolate chips.

Rocks are also made of ingredients. The ingredients in rocks are called

minerals.

Gneiss, granite and sandstone are common rocks that are made from a mixture of the minerals feldspar, quartz and mica.

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The closer we look at a rock, the more we may see the different minerals in the mixture.

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• Calcite• Feldspar• Galena• Gold• Graphite• Hematite

There are many hundreds of different minerals that make all the rocks on Earth. We only need to identify a few of the most common minerals in 4th and 5th grade.

• Hornblende• Magnetite• Mica• Pyrite• Quartz• Talc

In order to study minerals we need some samples of the pure minerals

(not mixed with other minerals to make rocks).

• Hardness• Color• Streak• Luster• Cleavage• Fizz

Some properties of minerals

Different minerals have different properties. A property is a way to tell one kind of thing from another. All samples of a one kind of mineral will have very similar properties.

Fourth graders do tests with mineral samples to discover their properties, then find the name of the mineral of the Mineral Identification Chart.

Hardness is the property of how difficult it is to scratch a mineral.

Some minerals are so hard that they can scratch glass.

Some minerals are so soft you can scratch them with a fingernail.

See the “Mineral Hardness” Powerpoint to learn more.

The Moh’s Hardness Scale is used by geologists to rate mineral hardness on a scale from 1 to 10. There are a lot more than 10 minerals in the world, but the ten on the Moh’s Hardness Scale happen to have the hardness of the number they represent.

Color is an easy mineral property to see.

But some minerals can be found in more than one color.

These mineral samples are all quartz. Gypsum is a mineral that can be white, gray or colorless.

Streak is a property that is only seen by rubbing the mineral on a special tile. Streak means the color of the streak the mineral makes on a tile.

Usually the streak is the same color as the mineral, but sometimes it is a different color. Some mineral’s streak is colorless (no streak).

Hematite is a black or gray mineral, but leaves a reddish-brown streak.

Luster is the property of how a mineral reflects light (how shiny it is).

We will only be noting if our minerals have a metallic or non metallic luster.

These minerals have a nonmetallic luster.

These minerals have a metallic luster. They shine like metal.

Cleavage is the property of how a mineral breaks. Some minerals have no cleavage (they fracture).But some minerals have cleavage that makes them easy to identify.

The cleavage of calcite makes it break into piece that are always the same shape.

Many minerals have no cleavage. When they are broken they fracture into odd shapes.

Mica has a cleavage that splits into thin flakes.

Calcite is a common mineral that has the property of fizz. A strong acid makes it fizz loudly and make lots of gas bubbles.

Some minerals fizz (make bubbles)

in a chemical reaction when they are exposed to acid.

Calcite or any rock containing calcite will make small bubbles even in a weak acid such as vinegar.

Identifying minerals is like detective work. We investigate and find clues to get the answer to the question, “What mineral is this?”

Clues

Color- white

Streak – white

Luster- nonmetallic

Hardness - 2 or 3

Cleavage – no

Fizz - yes

Suspects:

Calcite

• Mineral Identification

You can find out more about identifying

minerals on Brainpop

Also by watching Mr. Harper’s Powerpoint called Mineral Hardness.