Classifying Rocks

What is rock?
Rock is a naturally formed solid
that is usually made up of one or
more types of minerals.
Three types of rocks:
1. Igneous
2. Sedimentary
3. Metamorphic

Essential Learning: I can identify the three
different types of rocks.
Igneous rocks: forms when molten rock (magma/lava) cools and becomes solid.
Sedimentary rocks: forms when pieces of older rocks, plants, and other loose
materials get pressed or cemented together.
Metamorphic rocks: formed when heat or pressure causes older rocks to
change into new types of rocks.
Rock Cycle: is the set of natural process that form, change, break down, and
re-form rocks.
“What’s a Rock?”

Essential Learning: I can identify the three different types
of rocks.
Goto your lab table. In each of the tubs, try to identify the rock
type: Do this for samples 1-7. Write this in your notebook
1. Write the name down of the sample.
2. Do you see crystals or no crystals?
3. Do you see sediment, large or small or no sediment?
4. Do you see fossils?
5. Do you see bands or lines in the sample? Different colors?
6. Do you think it is Igneous, Sedimentary or Metamorphic?
Why do you think this?

Essential Learning: I can explain the rock cycle.
Igneous rocks
Sedimentary rocks
Metamorphic rocks
Sediment
Weathering/erosion
Compaction/cementation
Magma
Melting
Cooling/crystallizing
Heat and pressure
Rock Cycle
Blue
Green
purple
yellow
Red

Essential Learning: I can explain how the rock cycle works and how it has no
end.

Essential Learning: I can identify different rock types.
Answer questions 1-6. Put these in your notebook. You need to finish during class. Focus and get it done.
1. How are rocks and minerals different?
2. What are the three types of rocks?
3. Which rock types are most common within Earth’s crust? Which type is most common at Earth’s
surface?
4. Why is the set of natural processes by which rocks change into other types of rocks called a cycle?
5. Which type of rock would you expect to be common on the floor of a large, deep lake? Why?
6. Draw a diagram showing how an igneous rock could change into a metamorphic rock and how a
metamorphic rock could change into a sedimentary rock.

How igneous rocks are formed?
IGNEOUS ROCK (Latin)
“From Fire”
Igneous rocks: forms when
molten rock cools and
becomes solid. (solidifies)
Form from Magma or Lava.

Texture of Igneous rock…
Intrusive Igneous rock
 Forms when magma cools within
earth.
 High temp allows magma to cool
slowly.
 Slow cooling allows time for LARGE
mineral crystals to form.

Diorite
Granite Gabbro
Intrusive Igneous rock

Texture of Igneous rock…
Extrusive Igneous Rock
 Forms when lava cools on earths
surface.
 The lower temp cause the lava to
cool quick.
 No time for mineral crystals to
form.

Pumice
Rhyolite Basalt
Extrusive Igneous rock
Obsidian

Composition of Igneous Rock
SILICA- a compound of silicon and oxygen. SiO2
Felsic Magma - Thick magma, high in SILICA.
 Contains very little calcium, iron or magnesium.
 Typically LIGHTER in color and less dense.
Mafic Magma - Thin magma, low in SILICA.
 Contains lots of iron, calcium and magnesium.
 Typically DARKER in color and denser.

Igneous Rock Lab.
1. Name
2. Intrusive or Extrusive.
3. Texture: Glassy, Fine, Coarse or Very Coarse
4. Color: Light or Dark
5. Silica rich or Silica poor
6. Felsic or Mafic
7. Minerals found in it. Follow the lines down
Do this for all 7 samples. Please and thank you.

Sedimentary Rock
Sedimentary Rock- rocks that form
when sediments become pressed or
cemented together or when sediments
precipitate out of solution.
Sediments- Materials that settle out
of water or air. These can be loose
pieces of rock, minerals, plant and
animal remains.

Sedimentary Rock
How do they form?
•From rock particles cementing together:
- Gravel, Sand, Silt/Clay
Sandstone Shale
Conglomerate

Four common steps in this formation:

From plants or shellscementing together:

Dissolvedmineralsre-formfrom water:

Sedimentary rocks show the action of wind and water. They
tell us the story about past environments.

Sedimentary Rock Lab.
1. Name
2. Texture: Clastic, Crystalline, Bioclastic
3. Grain Size...
4. Composition category...
5. Comments category...
6. Fossils? Describe if present.
7. How do you think if formed?
Compaction Cementation, water solution, evaporation
8. Other observations?
Do this for all samples. Please and thank you.

Metamorphic Rock
Metamorphism- Process by which existing rock
is changed by heat/pressure or both!
The beginning rock can be:
 Igneous
 Sedimentary
 Metamorphic

How Metamorphic Rocksare Formed
Recrystallization- Pressure and
heat breaking atoms bonds and
minerals recrystallize.
Metamorphic changes occur in
different areas.
• Contact Metamorphism- Small
areas.
- Cause Magma
• Regional Metamorphism- Large
areas.
-Cause Plate Movement

Metamorphic Rocks develop bands of
minerals.
Foliation- arrangement of minerals in
flat or wavy bands.
Foliated Rocks: when mineral grains
line-up in parallel bands it is said that
it has a "foliated texture".
Examples:
slate, phyllite, schist and gneiss

Foliated Metamorphic Rocks
Examples:
phyllite
slate gneiss
schist

Metamorphic Rocks develop bands of
minerals.
Foliation- arrangement of minerals in
flat or wavy bands.
Non-Foliated Metamorphic Rocks: a
metamorphic rock where no banding
occurred. The grains change, grow,
and rearrange but don’t form bands.

Non-Foliated Metamorphic Rocks
Examples:
quartzite
marble
(Sandstone = quartzite)
(Limestone = marble)

IF you were walking down the
streets and you came across
these rocks, what could you
tell a stranger about them?
How did they form?
Use foliated and
nonfoliated in your
response.
One is a gneiss and on is a
quartzite.

Metamorphic Rock Lab.
1. Name
2. Texture: Foliated (mineral alignment or Banding) or Nonfoliated
3. Grain Size: Fine, Fine to Medium, Medium to Coarse or Coarse
4. Composition category…
5. Type of Metamorphism: Regional or Contact
6. Comments category...
7. Other observations?
Do this for all samples. Please and thank you.

Classifying Rocks

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