1.
2.
3.
The contribution of minerals to rock
composition.
Classify rocks by their process of formation.
Describe processes that change rocks and
the surface of the earth.
More specifically:
1.
2.
Characteristics used to identify rocks
Identify and describe the 3 major rock
groups.

A rock is a naturally occurring solid
mixture of one or more minerals, or
organic matter

Earth’s crust is made of rocks.

Rocks are classified by how they
are formed, their mineral
composition, and their texture

Rocks change over time through
the rock cycle
1.
2.
Rocks are made of mixtures of minerals
and other materials.
Ex: granite is made of the minerals quartz,
feldspar, hornblende, and mica.
What is the difference between a rock and a
mineral?
4. Mineral- is naturally occurring and cannot be
made of once living things.
5. A rock can have minerals in it, but minerals will
NEVER have rocks in them.
3.
6.
Scientists classify rocks by color, mineral
composition, and texture.
A rock’s color
provides clues to the
rock’s mineral
composition
2. Ex: granite is lightcolored rock that has
high silica content.
3. Ex: basalt is a dark
colored rock that is
low in silica.
1.
1.
2.
3.
4.
Particles of minerals and other rocks that
make up a rock are called grains.
Grains give the rock its texture- the look and
feel of the rock’s surface.
Ex: smooth or rough, glassy or chalky.
Page 56
1.
Grain size
a. Large and easy
to see- coursegrained-ex:
diorite
b. Small- fine
grained- ex:
slate
c. No visible grainex: flint
1.
2.
3.
Grain shape results
from the
fragments of
several rocks or
the shapes of the
crystals that form
the rock.
Rounded grainex: conglomerate
Jagged grain- ex:
Breccia

Conglomerate is determined by the shape of
the fragments of other rock.

Granite is determined by the shape of the
rock’s crystals.
1.
2.
Nonbanded(nonfoliated) ex:
quartzite- no
grains b/c it cooled
very quickly.
Banded- ( foliated)
ex: gneissdifferent colors in
the bands.
1.
2.
3.
4.
What are the three ways geologists classify
rocks?
What does banded and nonbanded mean?
What does course grained and fine grained
mean?
Name an example of a rounded grain rock
and a jagged grained rock?
1.
Geologists classify rocks according to their
origin (how they formed). Three groups are:
a. Igneous Rocks- forms from cooling of
magma/lava. Ex: granite and basalt
b. sedimentary rock- forms when particles
of other rocks are pressed and cemented
together. Ex: conglomerate and limestone
c. metamorphic rock- forms when a rock is
changed by heat and pressure. Forms deep
underground. Ex: gneiss and shale


Igneous rock begins as magma or molten
rock.
Magma can form:
▪ When rock is heated
▪ When pressure is released
▪ When rock changes composition
http://www.fi.edu/fellows/payton/rocks/create/igneous.htm

Intrusive Igneous Rocks:
magma cools below (INSIDE)
the Earth’s surface

Extrusive Rocks: forms when
magma erupts OUTSIDE
(EXIT) the Earth’s surface
(lava), cools quickly with very
small or no crystals formed
http://www.windows.ucar.edu/tour/link=/earth/geology/ig_intrusive.html&edu=high&fr=t
BASALT




dark colored (mafic)
forms from lava
forms the ocean’s crust
(floor), shield volcanoes,
and lava plateaus
It is the most common
extrusive igneous rock.
GRANITE
light colored (felsic)
forms from magma
forms the core of mtn
ranges
 It is the most abundant
intrusive rock in the crust.







Felsic: light colored rocks that are rich or
high in silica(silicon and oxygen).
Mafic: dark colored rocks that are poor or
low in silica.
Coarse-grained: takes longer to cool, giving
mineral crystals more time to grow (bigger
crystals)
Fine-grained: cools quickly with small or no
crystals
Coarse-Grained
Fine-Grained
Felsic
Granite
Rhyolite
Mafic
Gabbro
Basalt



Large crystals surrounded by small crystals.
Cools in two stage, quick then slow.
Looks like Jello filled with fruit
Obsidian is a dark-colored , smooth and shiny volcanic glass that forms from
the very rapid cooling of molten rock material. It cools so rapidly that crystals
do not form.
Is this rock Felsic or
Mafic?
Is it fine-grained or
coarse-grained?
Is this rock Intrusive or
Extrusive?
Mafic, fine grained, extrusive



Minerals determine the color of rocks.
Ex: Reddish granite is rich in feldspar and is
speckled pink. Hornblende and dark mica
cause granite to be light gray with dark
specks. Quartz makes with light gray or
smoky specks.
Geologists take thin slices of granite and
study them under the microscope to
determine its mineral composition.


Igneous rocks are hard, dense, and durable.
Thus the reason they were used in building
materials.
Several ways igneous rocks have been used
are:
 Egyptians used them to build statues
 Incas used them to build a fortress near their
capital city
 United States used them to build bridges and
buildings and to pave streets with cobblestones in
the 1800’s and early 1900’s.

Basalt is used for
gravel for construction
and also for soil mixes.

Pumice is used for
cleaning and polishing.
1.
2.
3.
How are igneous rocks made?
If a rock is course grained, did it cool fast or
slow? What about fine grained?
What are the two types of igneous rocks and
where did they form?



Sediment includes small, solid pieces of rock,
minerals, and organic matter such as shells,
bones, leaves, and stems.
Water and wind deposit particles that form
sedimentary rocks.
Running water, wind, and ice carry sediment
from one place to another.



When sediments are pressed and squeezed
together, compaction takes place.
When dissolved minerals naturally glue
sediments together, cementation takes
place.
Rock fragments that are carried by water
eventually sink to the bottom of a lake or
ocean.




•
Sedimentary rock is formed by erosion
Sediments are moved from
one place to another
Sediments are deposited in
layers, with the older ones
on the bottom
The layers become compacted
and cemented together which
then turn in to sedimentary rock.
This takes millions of years.
http://www.fi.edu/fellows/payton/rocks/create/sediment.htm

Sedimentary Rocks are formed at or near the
Earth’s surface

No heat and pressure involved

Strata – layers of rock

Stratification – the process in
which sedimentary rocks are
arranged in layers


Geologists classify sedimentary rocks
according to the type of sediments that make
up a rock.
Three Types
 C – O- C
 1. Clastic
 2. Organic
 3. Chemical
 Different processes form each type of
sedimentary rock.
Clastic – made of fragments of rock squeezed
and cemented together with calcite or quartz.
Breccia is a term most often
used for clastic sedimentary
rocks that are composed of
large angular fragments
(over two millimeters in
diameter).
The spaces between the
large angular fragments can
be filled with a matrix of
smaller particles or a mineral
cement that binds the rock
together.
They are classified by
the SIZE of the rock
fragments.
 EX: Tiny particles of
clay is shale
 Sandstone is small
particles of sand
 Conglomerate is
different sized rock
fragments.

Organic sedimentary – remains of plants and
animals Ex: coal and limestone
Coal is an organic
sedimentary rock that
forms from the
accumulation and
preservation of plant
materials, usually in a
swamp environment.
Coal is a combustible rock
and along with oil and
natural gas it is one of the
three most important
fossil fuels.

Shells from living things pile up on the ocean
floor in layers. Compaction and cementation
change sediments to limestone.
Chemical sedimentary – minerals crystallize
out of solution to become rock. Mineral
deposits forms when seas or lakes evaporate.
Limestone is also a chemical
sedimentary rock composed
primarily of calcium carbonate
(CaCO3) in the form of the
mineral calcite. It most
commonly forms in clear, warm,
shallow marine waters.
It is usually an organic
sedimentary rock that forms
from the accumulation of shell,
coral, algal and fecal debris.



Rock Salt crystallizes from the mineral halite.
Sandstone and limestone are soft enough to
be cut easily into blocks or slabs. That’s why
they have been used as building materials for
thousands of years.
The White House in Washington D.C. is made
of sandstone.

People use sandstone and limestone today to
decorate or cover the outside of walls of
buildings. Cement is made out of limestone.
1.
2.
How do sedimentary rocks form?
Name the category for each rock: clastic,
organic, or chemical
1. Coal
2. Conglomerate
3. Limestone
 Meaning to change shape
 Changes with temperature
and pressure, but remains
solid
 Usually takes place deep in
the Earth
http://www.fi.edu/fellows/payton/rocks/create/metamorph.htm


Contact Metamorphism – heated by nearby magma
Increased temperature changes the composition of
the rock, minerals are changed into new minerals
Hornfeld is a fine-grained nonfoliated metamorphic rock produced
by contact metamorphism
http://www.windows.ucar.edu/tour/link=/earth/geology/meta_contact.html&edu=h igh&fr=t

Regional Metamorphism –
pressure builds up in rocks
that is deep within the Earth

Large pieces of the Earth’s
crust collide and the rock is
deformed and chemically
changed by heat and pressure
http://www.windows.ucar.edu/tour/link=/earth/geology/meta_regional.html&edu=high&fr=t

Two Types
 1. Foliated (banded)
 2. Nonfoliated (nonbanded)

Foliated (banded) - contain aligned grains of
flat minerals (it forms layers).
Gneiss is foliated
metamorphic rock
that has a banded
appearance and is
made up of granular
mineral grains.
It typically contains
abundant quartz or
feldspar minerals.

Non-Foliated (nonbanded)– mineral grains
are not arranged in plains or bands
Marble is a nonfoliated metamorphic
rock that is produced
from the
metamorphism of
limestone.
It is composed
primarily of calcium
carbonate.

Determine if the following rock samples are
foliated or non-foliated:
Amphibolite
Quartzite
Phyllite
Foliated
1.
2.
3.
How do metamorphic rocks form?
What does foliated and nonfoliated mean?
Give an example of a foliated rock and a
nonfoliated rock in that order.

www.brainpop.com
 Types of Rock
 Rock Cycle

http://www.youtube.com/watch?v=rkGVE6w
NAzo - Mr. Lee

http://www.youtube.com/watch?v=lE3jR_Rhx
O4 – Mr. Parr