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AIM: Where do igneous rocks form and how can we tell just by looking at them?

Do Now:

Mineral and Rock graphic organizer “Bingo” game

Rearrange the pieces until you can formulate 3 sentences about rocks and 3 sentences about minerals.

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The Rocks:

Rocks are naturally formed solids composed of one or more minerals, organic materials, glasses, and fragments from other rocks.

There are three types; igneous, sedimentary, and metamorphic.

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IGNEOUS ROCKS

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Igneous rocks form when molten (liquid) rock cools and hardens.

Igneous Rocks

Solid Rock

-As it cools, crystals/minerals form until it is completely solid.

-Solidification = crystallization.

Crystal = Mineral.

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Magma – molten material BELOW the surface of the Earth

Lava – molten material AT OR ABOVE earth’s surface

MAGMA VS. LAVA

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Intrusive rock: when magma cools Inside Earth

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Extrusive rock: when lava has Exited and cools outside Earth

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COOLED SLOW beneath the surface, so large minerals have time to grow.

COOLED FAST at the surface, so either there are no minerals or they are so small they are not visible.

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Intrusive Rocks

Slow cooling rate = large crystals

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Extrusive Rocks

Fast cooling rate = small crystals

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Pop quiz hot shot!!!

Fine grained

Basalt

Large crystals

Granite

How can you tell which rock is formed intrusively?

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ESRT…..p6

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HOLD ON A SECOND…

Texture – How the rock’s surface looks due the mineral crystal size.

*NOT HOW THE ROCK FEELS!

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Mineral/Crystal Texture

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The mineral crystal size

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Non vesicular = No bubbles

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Where the rock formed

Exited Earth

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Where the rock formed

Inside Earth

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AIM: �Where do igneous rocks form and how can we tell just by looking at them?

Do Now:

Igneous Rock Fun Fact

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Lets see what these words mean.

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Contains aluminum	Contains magnesium & iron
Light colored	Dark colored
Typical continental rock composition	Typical oceanic rock composition

Felsic

Mafic

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Practice identifying igneous rocks #1

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Lets try to identify an unknown igneous rock

Observed properties of the unknown rock:

1. Light colored

2. Low Density

3. Fine Grained

4. Non vesicular (No gas bubbles)

Use the E.S.R.T.

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All the rock names are located in this area

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Now we have to see where all our known properties meet in the rock name area

The rock could be any in the highlighted area, according to color and density

We need to use texture to narrow it down further

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The texture was fine and non vesicular

The only place these two textures match is right here

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The correct rock is located in the area where all the properties overlap.

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What do we think our mystery rock is?

Yup, It is a sample of Rhyolite, an extrusive igneous rock

Identifying any other igneous rock works the same way!!!

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Now lets take our sample of rhyolite and find out what its mineral composition is.

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Here are the mineral composition percentages

If you do not know where in the rock rectangle to go, assume it is right in the middle.

Middle

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All of this equals 100% of the rock’s mineral composition.

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