Rocks

1. ROCK
EARTH AND LIFE SCIENCE

2. Review:
 Arrange the jumbled letters to find the appropriate criteria to
determine whether a material is classified as a mineral or not.
1. N L T L A U R Y N G O I R U C
C
______________________-a term which identifies
minerals as part of Earth’s natural processes.
2. C A I I R O G N
______________________- means a substance is not a
product of an organism but rather of Earth’s physical
processes.

3. 3. S O U E N E G O M O H D I L O S
_____________________- have definite shape and
volume.
4. E N I L L AT SY R C E S RT R U C UT
_____________________- atoms are arranged in
order of increasing pattern.
5. L M C E H A I N O IT O C M O P S I
____________________- represented by chemical
formula.

4. Objective:
1. identify the three types of rocks;
2. classify rocks as to igneous,
sedimentary and metamorphic rocks;
and
3. appreciate the importance of rocks
in our daily life.

5. ROCK
 is a naturally occurring solid aggregate of one
or more minerals.
 Are made up of different minerals
 Petrology is the scientific study of rocks.
Petrologists classify rocks based on how they
were formed. (derived from the Greek words
“petra” which means “rock” and “logos” which
means “study”)
 Rocks are classified by how they are
formed!!!

6. Rocks
Monomineralic
 1 Mineral
Polymineralic
 More than 1 Mineral
 Rocks are classified by
how they are formed!!!

7. Rock
ROCKS change over time through
the Rock Cycle

8. 3 Types of Rocks
There are 3
different
types of
rocks;
 Igneous
 Sedimentary
 Metamorphic

11. Igneous Rock
Igneous rocks are formed by magma and lava as it cools.
-formed from hardening and crystallization of magma or molten
material that originates deep within the earth.
Igneous rocks form in two different ways.
 The term “igneous” is based from the Latin ignis, meaning fire.
 Rock that comes from lava cools very fast and can either be very
light and airy or the rocks can be glassy.
 Rocks that come from magma are formed under ground. They are
often times very hard and have more colors.

12. Igneous rock
Magma can form:
When rock is heated
When pressure is released
When rock changes
composition
Magma is a mixture of many
minerals

13. Two types of igneous rock:
A. Extrusive/Volcanic rock - forms
when magma makes its way to
Earth’s surface as lava and then
cools.The crystals are very small
(fine-grained) since the cooling
process is fast.
B. Intrusive/Plutonic - It cools
slowly beneath the Earth
surface and are created
by magma.The intrusive
igneous rocks have very large
crystals (coarse grained).

14. Intrusive
 Cools below the
earths surface
(slowwwwly!)
 Magma
 “Plutonic”
Extrusive
 Cools at the Earths
surface (quickly!)
 Lava
 “Volcanic”

15. The longer the rock takes to cool, the larger
the crystals!
 Cools slow …..Large crystals
 Cools fast …….small crystals
 Cools immediately……NO Crystals (glass)

16. Classification of Igneous Rock
1. Composition- it refers to rock’s mineral and
chemical make-up.
 Felsic – igneous rocks that are light in colors;
feldspar and silicates
 Mafic – dark-colored igneous rocks made up of
magnesium, calcium and iron
 Intermediate – refers to igneous rocks
between mafic and felsic composition.
 Ultramafic – denotes igneous rocks that
composed chiefly of mafic minerals.

17. Igneous Rocks

18. Classification of Igneous Rock
2. Texture - overall appearance of a rock based on the size,
shape, and arrangement of interlocking mineral crystals.
Aphanistic – fine-grained rocks with crystals seen by aid
of microscope.
Phaneritic - coarse-grained rocks
Porphyritic – large crystals with small crystals
Glassy - a rock that looks like colored glass with no
visible mineral crystal.
Pyroclastic- results from explosive fragmentation of
volcanic material.
Examples:
Obsidian, pumice, basalt, granite, diorite, gabbro

20. Vesicular- gas pockets

21. Igneous Rocks
Obsidian is a dark-colored 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

22. Sedimentary Rock
 Sedimentary rock is made
when sediments (sand,
gravel, and dirt) are
pressed together over time
and become a rock
 Sedimentary rock is
formed in layers.

23. Sedimentary Rock
 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

24. Sedimentary Rock
 provide information about surface
conditions that existed in the Earth’s past.
 Particles of sand, shells, pebbles, and other
fragments of materials called sediments,
accumulate in layers and over long period
of time harden into rocks.
 Compaction-due to increase of pressure of
layered sediments it bind together to form
the sedimentary rocks.

25. Sedimentary Rocks
Limestone
Shale
Sandstone
Granite

26. Three types of sedimentary rocks
a. Clastic Sedimentary rock - formed from
accumulation of clasts: little pieces of broken
rocks and shells. Examples: conglomerate,
breccia, sandstone, shale
b. Chemical - formed when dissolved minerals
precipitate from a solution.
Example: Halite - formed when a body of
seawater becomes closed off and evaporates.
c. Organic - rocks formed from the
accumulation of animal debris
Example: Coal - composed of organic matter
in the form of plants fragments.

28. Metamorphic Rock
 Metamorphic rocks are made from other
rocks. Metamorphic means to change.These
rocks are often formed from the mountains.
 The pressure and heat changes these rocks.
 Heat and pressure help change an igneous or
sedimentary rock into a new kind of rock
(think about how a caterpillar becomes a
butterfly)

29. Metamorphic:
 Rocks that are changed due to extreme heat
and/or pressure.
 DO NOT MELT!!! (they recrystalize)
Metamorphic rocks become…
1. Harder
2. More dense
3. Banded or foliated
4. Distorted

30. Metamorphic Rock
 forms from pre-existing rocks: either
metamorphic, igneous, sedimentary or
other metamorphic rocks that have been
altered by agents of metamorphism.
 Examples: quartzite, marble, slate, phyllite
 Metamorphism –
transformation
of one rock type into
another.

31. 2 types of metamorphism
1. Regional-due to changes in pressure
and temperature over large region of the
crust. It may happen when rock is buried
deep below the surface of the earth.
2. Contact-the rock minerals and textures
are changed mainly by heat due to
contact with magma.

32. Classification:
1.Texture - refers to the size arrangement and grains
within the rock.
Foliation - any planar arrangement of mineral grains
or structural features within the rock.
a. Foliated rocks – can be arranged in terms of
increasing metamorphism, and it appeared layered
or banded with compressed mineral grains. Example:
mica
b. Non-foliated rocks – usually made up of only few
minerals.

33. Banding

34. Foliated

36. Identifying Characteristics of
Rocks
Igneous
 Intergrown crystals
 Glassy texture
Sedimentary
 Cemented fragments
(sediments)
 Fossils
 Organic material
Metamorphic
•Banding
•Foliated

39. The Rock Cycle

40. PARTS OF ROCKS

41. Rocks have many different parts
 Rocks can be sorted into groups
by looking at their parts. Some
rock parts are:
 Crystals
 Grains

42. Crystals
 Crystals are different atoms that are formed
in a pattern. They can be big or small, fat or
thin.

43. Grains
 Grains are smaller pieces of rock or sediment.
Grain size is something that is used a lot to
help decide the rock type.

44. ASSIGNMENT
Pick a 3 rocks on your
way home and bring
tomorrow.

45. Rock Explorers
 Lets look at some rocks!
 Get a partner and a magnifying glass
 Come and pick up a rock (you will be looking
at one rock at a time)
 You and your partner will take turns looking
at the rock. Decide if you think that crystals
are large or small. Look to see if it has grains.

47. 1.Tectonic burial
2. Sedimentation
3. Erosion
4. Metamorphic rock
5. Sedimentary rock
6. Magma
7. Igneous rock
8. Melting of rock and minerals
9. Crystallization

48. Answer:
1.Magma
2. Crystallization
3. Igneous rock
4. Erosion
5. Sedimentation
6. Sedimentary rock
7.Tectonic burial
8. Metamorphic rock
9. Melting of rock and minerals