Rocks & Minerals

THE DIFFERENCE BETWEEN ROCKS & MINERALS

•It is not easy to tell the difference between rocks & minerals because there are so many kinds of them. There are 3000 known minerals on

Earth!There are 3 main rock types but hundreds of sub-categories

It takes years of study to be able to accurately identify a mystery rock and even then geologists want to know where the specimen came from.

First the basics:

2. A rock is made up of 2 or more minerals.

1. All rocks are made of minerals.

3. You need minerals to make rocks, but you don't need rocks to make minerals.

Think of a chocolate chip cookie as a rock. The cookie is made of flour, butter, sugar & chocolate

The cookie is like a rock and the flour, butter, sugar & chocolate are like minerals.

Leave MY

cookies alone!

In your notes finish this sentence: A chocolate chip cookie is like a rock . . .

The three types include:

Rocks are divided into: 3 Types

They are classified by:

How they were formed

1. Igneous

2. Sedimentary

3. Metamorphic

Rock Words: There are many common names for rocks and the usually give you an idea of how big the rock is. Here are a few:

- huge, giant hunk of rock that is still attached to the earth's crust, doesn't move, tall

- large, taller than a person

- large, you could get your arms around it or a bit smaller but it is usually jagged, broken off a bigger piece of rock

- round rocks that are along the edge & at the bottom of fast-flowing rivers

- medium, you could hold it in two hands

- small, you can hold it with two fingers, could get stuck in your shoe, usually rounded

- made up of tiny pieces of rock, grains of sand

- tiny, like a grain of rice or smaller, often found on a beach

mountain

boulder

rock

river rock

stone

pebble

sand

grain

The rocks you see around you - the mountains, canyons & riverbeds, are all made of minerals

So . . . What is a MINERAL?

4. A mineral is composed of the same substance throughout - if you were to

cut a mineral sample, it would look the

same inside and out

1. A solid NOT a gas or liquid

2. Naturally forming NOT man-made

3. Inorganic NOT living

90% of the Earth’s crust are

SILICATE minerals

Characteristics used in the identification

& study of minerals

1. Color – this varies depending on the

chemicals present and is the

least informative (reliable) in

identifying a mineral because it

can change or the same mineral

can come in a variety of colors

Both of these samples are the mineral fluorite.

2. Luster –

What the surface looks like in the light –

is it shiny or dull?

3. Hardness –

What it can scratch & What scratches it

Scratching tools:•fingernail (2.2)•copper penny (3.5)

•pocket knife or common nail (5.2)•piece of glass (5.5)•steel file or concrete nail (7.5)•piece of corundum (9)

5. Fracture - is when a mineral breaks, but the surface is not regular, does not show cleavage.

4. Cleavage - is when a mineral breaks with smooth flat surfaces.

6. Density / Specific Gravity – how heavy it feels, heft

7. Tenacity - is how tough a mineral is, how easily a mineral will break, split, crumble or change shape.8. Transparency - The ability to transmit light.

•Transparent•Translucent•Opaque

9. Streak –

The color of the mineral in powdered form.

The mineral is rubbed against a piece of unglazed porcelain called a streak plate.