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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.
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