Transcript ppsx

Identifying Common Igneous Rocks
Igneous rocks are composed of a variety of minerals
that contribute important classification characteristics.
Click here to see two classification methods
Step 1: Describe the rock’s texture
Coarse
Fine
Step 2: Describe the rock’s color.
Light Color
Intermediate
Color
Dark Color
Step 3: Where does this place you on the chart and
what is the name of this igneous rock?
Click on a name in the chart to find out if you are correct.
Step 1: Describe the rock’s texture
Coarse
Fine
Step 2: Describe the rock’s color.
Light Color
Intermediate
Color
Dark Color
Step 3: Where does this place you on the chart
and what is the name of this igneous rock?
Click on the name to find out if you are correct.
Step 1: Describe the rock’s texture
Coarse
Fine
Step 2: Describe the rock’s color.
Light Color
Intermediate
Color
Dark Color
Step 3: Where does this place you on the chart and
what is the name of this igneous rock?
Click on the name to find out if you are correct.
Step 1: Describe the rock’s texture
Coarse
Fine
Step 2: Describe the rock’s color.
Light Color
Intermediate
Color
Dark Color
Step 3: Where does this place you on the chart and
what is the name of this igneous rock?
Click on the name to find out if you are correct.
Step 1: Describe the rock’s texture
Coarse
Fine
Step 2: Describe the rock’s color.
Light Color
Intermediate
Color
Dark Color
Step 3: Where does this place you on the chart
and what is the name of this igneous rock?
Click on the name to find out if you are correct
Step 1: Describe the rock’s texture
Large Crystals
Small Crystals
Step 2: Describe the rock’s color.
Light Color
Intermediate
Color
Dark Color
Step 3: This rock is known for its salt and pepper appearance.
Step 4: Where does this place you on the chart
and what is the name of this igneous rock?
Click on the name to find out if you are correct
These three igneous rocks are not on the texture vs. color chart.
Can you pick out the characteristic that helps identify each one?
This is light colored PUMICE.
Which term best describes its texture?
Vesicular
Or
Glassy
Vesicular? Click here
This is dark colored SCORIA.
Which term best describes its texture?
Vesicular
Or
Glassy
Pumice and scoria are both full of empty gas voids. In pumice, the tiny voids are
not well interconnected. The larger ones in scoria are interconnected. Is this
enough of a hint to figure out pumice’s unique characteristic?
See answer!
This is black OBSIDIAN.
Which term best describes its texture?
Vesicular
Or
Pumice
floats on
water!
Glassy
Igneous Rock Texture, Cooling Rate, and Origin Location
In most cases, the texture of an igneous rock provides a clue that suggests how quickly, in relative terms of fast vs. slow, the molten
magma or lava took to cool into solid rock. The concept is really simple:
The slower the molten material cooled, the coarser the texture of the igneous rock.
An extension of this idea is that molten magma or lava will cool differently depending on physical location.
Lava, molten rock expelled onto Earth’s surface, will cool relatively quickly.
On the other hand, magma, molten rock trapped inside Earth, will cool much more slowly.
Can you develop a simple conceptual model that explains this phenomena?
Click here to check your idea
Think you understand? Complete the following sentence by clicking on the correct response.
on Earth’s surface.
magma
Basalt, a fine grained igneous rock formed as a molten mass of
cooled
lava
inside Earth.
You should be able to construct a similar sentence for the coarse grained igneous rocks, such as granite.
Now for the really good stuff!!
The mineral composition and chemistry of rhyolite and
granite are the same! The only difference is their texture
due to cooling rate. Which is the intrusive version? Click
a photograph below to confirm your answer
Granite
Rhyolite
The mineral composition and chemistry of gabbro and
basalt are the same. The only difference is their cooling
rate. Which is the extrusive version? Click a photograph
below to confirm your answer.
Gabbro
Obsidian is a well known volcanic rock. Its texture is fine grained and
looks like glass. It also breaks with the same kind of unique conchoidal
fracture pattern that glass does. Is obsidian intrusive or extrusive? What
event(s) had to transpire to turn molten rock into a hunk of black glass?
And, what’s conchoidal? Time for you to do some research on your own.
Obsidian
Basalt
Almost done!
Apply your knowledge of igneous rocks.
1.
Print the next page.
2.
Name the five igneous rocks. Write the name of the rock beside it on your printed page.
3.
Ask your teacher to verify your decision.
4.
Be prepared to explain the process you used to identify each rock.
5.
The pictures are new. Don’t memorize images of rocks, use the process of characteristics.
6.
The last page is an expanded version of the igneous rock chart. It may be of help.
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