Transcript Rocks, Minerals & the Rock Cycle

Rocks, Minerals & the Rock Cycle
Chapter 16
Section 1 Minerals and Mineral
Resources
Objectives
• Define the term mineral.
• Explain the difference between a metal and a
nonmetal, and give two examples of each.
• Describe three processes by which ore minerals
form.
Mineral Resources
• We depend on the use of mineral resources in
almost every aspect of our daily life.
• However, our dependence on minerals has not
come without a price.
• The current challenge is to obtain the minerals
that an ever-increasing world population
demands at minimal cost to the environment.
Mineral Consumption per Person
(U.S.)
What Is a Mineral?
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A mineral is a naturally occurring, usually inorganic
solid that has a characteristic chemical
composition, an orderly internal structure, and a
characteristic set of physical properties.
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Minerals are made up of atoms of a single element,
or of compounds. A compound consists of atoms
of two or more elements chemically bonded
together.
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The atoms that make up minerals are arranged
in regular, repeating geometric patterns.
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Section 1 Minerals and Mineral
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What Is a Mineral?
The arrangement of the atoms, along with the
strength of the chemical bonds between them,
determine the physical properties of minerals,
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Some elements, called native elements, are
considered minerals. These include the elements
gold, silver, and copper.
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Most minerals, however, are compounds.
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The mineral quartz is made up of silica, which
consists of one silicon atom and two oxygen
atoms.
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Ore Minerals
An ore mineral is a mineral that contains one or
more elements of economic value.
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During the mining process, gangue minerals,
minerals with no commercial value, are extracted
along with ore minerals.
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Ore minerals, once separated from the gangue
minerals, are refined using various methods to
extract the valuable elements they contain.
•
For mining to be profitable, the price of the final
product must be greater than the costs of
extraction and refining.
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Ore
Minerals
Section 1 Minerals and Mineral
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Metallic Minerals
• Ore minerals are either metallic or nonmetallic.
• Metals have the following characteristics:
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can conduct electricity
have shiny surfaces
are opaque
• Many valuable metallic minerals are native
elements, such as gold, silver, and copper.
• Other important ore minerals are compounds of
metallic minerals with nonmetallic elements.
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Section 1 Minerals and Mineral
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Nonmetallic Minerals
• Nonmetals have the following characteristics:
• tend to be good insulators
• may have shiny or dull surfaces
• may allow light to pass through
• Nonmetallic minerals can also be native
elements or compounds.
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Section 1 Minerals and Mineral
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How Do Ore Minerals Form?
• Economically important ore deposits form in a
variety of ways, both on and beneath Earth’s
surface.
• The types of mineral that form depend on the
environment in which they form.
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Mineral Environments
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Section 1 Minerals and Mineral
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Hydrothermal Solutions
• Hot, subsurface waters that contain dissolved
minerals are called hydrothermal solutions.
• Hydrothermal solutions dissolve minerals as
they flow through cracks in rocks.
• New minerals crystallize out of these solutions
and then fill fractures to form ore deposits called
veins.
• Many economically valuable metallic ores form
in this way.
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Section 1 Minerals and Mineral
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Evaporites
• When water in the seas or lakes evaporate,
they leave behind deposits of salts called
evaporites.
• Evaporites form in arid regions where rates of
evaporation are high.
• Halite (rock salt) and gypsum are important
evaporite minerals.
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Section 1 Minerals and Mineral
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Mineral Resources and Their
• Uses
Certain metals are of major economic and
industrial importance.
• Some metals can be pounded or pressed into
various shapes or stretched very thinly without
breaking. Others conduct electricity well.
• Often two or more metals are used to form
alloys, which combine the most desirous
properties of the metals used to make them.
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Section 1 Minerals and Mineral
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Mineral
Resources and
Their Uses
Buildings
Roads
Bridges
Concrete
Extract minerals – like iron (Fe) to make
steel
Toothpaste
Salt
Sandpaper
Decorations
Jewelry
1. Why is it important to have a basic
understanding of the rock cycle?
Rocks contain clues about the environment.
Helps us understand the formation of the earth.
2. Rock
Any solid mass of minerals or mineral-like matter
3. Do most rocks occur as one
mineral or as a mixture of minerals?
4. Some rocks are made of nonmineral material, can you name one?
Coal - begins as layers of plant matter accumulate at the
bottom of a body of water. For the process to continue the
plant matter must be protected from biodegradation and
oxidization, usually by mud or acidic water. This trapped
atmospheric carbon in the ground in immense peat bogs that
eventually were covered over and deeply buried by
sediments under which they metamorphosed into coal.
Over time, the chemical and physical properties of the plant
remains (believed to mainly have been fern-like species
antedating more modern plant and tree species) were
changed by geological action to create a solid material.
Coal, a fossil fuel, is the largest source of energy for the
generation of electricity worldwide.
5. Explain the rock cycle.
A continuous process that causes rock to change
from one form to another
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The Rock Cycle is a group of changes, this change does not
necessarily have to be a chemical change.
Igneous rock can change into sedimentary rock or into
metamorphic rock.
Sedimentary rock can change into metamorphic rock or into
igneous rock.
Metamorphic rock can change into igneous or sedimentary
rock.
Almost all of rock today that we have on earth is made up of
all the same stuff as the rocks that dinosaurs and other
ancient life forms walked, crawled, or swam over
While the stuff that rocks are made of has stayed the same,
the rocks themselves, have not
Over time rocks are recycled into other rocks
Moving tectonic plates are responsible for destroying and
forming many types of rocks
6. List the 3 types of rocks
7. Igneous Rocks
Igneous rock forms when
magma cools and makes
crystals.
Magma is a hot liquid made of
melted minerals. When magma
pours onto the earth’s surface
it is called lava. The minerals
can form crystals when they
cool.
Igneous rock can form
underground, where the
magma cools slowly. Or,
igneous rock can form above
ground, where the magma
cools quickly.
The crystals grow together and
form one igneous rocks.
8. What kind of igneous rocks form
when molten lava cools and hardens?
Extrusive = forced out while
molten through cracks in the
earth's surface
9. What is the Latin word that the word
igneous comes from and what does it
mean?
ignis = fire
10. Intrusive Igneous Rocks
Form from magma below the earth’s surface
11. Extrusive Igneous Rocks
Formed by lava on the Earth’s surface
12. What is the difference
between magma and lava?
Magma = molten rock
below the earth’s
surface
Lava = molten rock
flowing on the earth’s
surface
13. What are the 8 elements that
make up magma?
Silicon, oxygen, aluminum,
iron, calcium, sodium,
potassium, magnesium
Look at the granite rock (A on age 71) and the rhyolite rock (B on page 71)
Granite
Rhyolite
14. In what ways are the two rocks similar?
Both are from melted rock
Their composition is the same
15. In what ways are the two rocks different?
Granite
Rhyolite
Granite – coarse texture, made from magma
Rhyolite – fine texture, made from lava
16. What causes the two rocks to be different?
Granite
Rhyolite
Granite – Slow cooling below the earth’s surface
Rhyolite – Quick cooling on the earth’s surface
17. Why do you think some rocks are
heavier than others?
Some are denser – less air space between particles
Which rock would have greater density?
Pumice
Granite
Classifying Rocks
Rocks can be
classified, or put into
groups with similar
characteristics, by
looking at the rocks
texture, mineral
composition, and
color.
18. What is texture?
The size, shape, and pattern of the rock’s grain
Glassy
(nice)
19. Composition (what’s it made of?)
The minerals that make up the
different parts of a rock
Examples:
Quartz
Feldspar
Magnesium
Iron
ADD
Rock Color
The apparent
color of the rock,
on the inside and
the outside
Metamorphic rocks are rocks
that have "morphed" into another
kind of rock.
These rocks were once igneous
or sedimentary rocks.
How do sedimentary and igneous
rocks change?
The rocks are under tons and
tons of pressure, which fosters
heat build up, and this causes
them to change.
If you exam metamorphic rock
samples closely, you'll discover
how flattened some of the grains
in the rock are.
Rock divisions occur in three
major families based on how
they formed: igneous,
sedimentary, and metamorphic.
Each group contains a
collection of rock types that
differ from each other on the
basis of the size, shape, and
arrangement of mineral grains.
Just remember 3 types of
rocks=3 divisions. (igneous,
sedimentary, and
metamorphic)
When classifying a rock sample geologists observe
the rock’s color and texture and determine its
mineral composition.
Texture: the size, shape, and pattern of the rock’s
grain.
Color: the apparent color of the rock, on the inside
and the outside.
Mineral composition: The minerals that make up the
different parts of a rock.
Texture: Grain Size
Often, the grains in a rock
are large and easy to see.
Such rocks are said to be
coarse-grained. In other
rocks, the grains are so
small that they can only be
seen with a microscope.
These rocks are said to be
fine-grained.
Notice the difference in
texture between the finegrained slate and the
coarse-grained diorite to the
right.
Texture: Grain Shape
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The grains in a rock vary widely in shape
Some grains look like tiny particles of fine sand
Others look like small seeds or exploding stars
In some rocks, such as granite, the grain results from the
shapes of the crystals that form the rock
• In other rocks, the grain shape results from fragments of
other rock
• These fragments can be smooth and rounded, like the
fragments in conglomerate, or they can be jagged, like
the fragments in breccia
• You can compare conglomerate and breccia one the
next slide
Texture : Grain Pattern
• The grains in a rock often form patterns. Some
grains lie in flat layers that look like a stack of
pancakes.
• Other grains form wavy, swirling patterns. Some
rocks have grains that look like rows of
multicolored beads, as in the sample of gneiss
shown above.
• Other rocks, in contrast, have grains that occur
randomly throughout the rock.
Different Types of Texture
Fine-Grained, Coarse-Grained, Rounded Grain, Jagged Grain,
Nonbanded, Banded
2 Types of Igneous Rocks
INTRUSIVE IGNEOUS ROCKS – When igneous rocks are
formed by magma that cools BENEATH Earth’s surface,
they are called intrusive igneous rocks
EXTUSIVE IGNEOUS ROCKS – When igneous rocks are
formed by LAVA ON Earth’s surface, they are called
extrusive igneous rocks
Lithification
• The process by which sediment becomes
sedimentary rock
• 1st step : erosion
• 2nd step : deposition
• 3rd step : compaction
• 4th step : cementation
Sedimentary Rocks : Erosion
Destructive forces are
constantly breaking up and
wearing away all the rocks
on Earth’s surface
The forces include heat and
cold, rain, waves, and
grinding ice
Erosion occurs when
running water or wind
loosens and carry away the
fragments of rock.
Sedimentary Rocks: Deposition
Eventually, the moving water or wind
slows and deposits the sediment.
If water is carrying the sediment, rock
fragments and other materials sink to
the bottom of a lake or ocean.
Deposition is the process by which
sediment settles out of the water or
wind carrying it.
After sediment has been deposited,
the processes of compaction and
cementation change the sediment
into sedimentary rock.
In addition to particles of rock,
sediment may include shells, bones,
leaves, stems, and other remains of
living things.
Over time, any remains of living things
in the sediment may slowly harden
and change into fossils trapped in the
rock.
Sedimentary Rocks: Compaction
At first the sediments fit together
loosely. But gradually, over millions
of years, thick layers of sediment
build up.
These layers are heavy and press
down on the layers beneath them.
Then compaction occurs.
Compaction is the process that
presses sediments together.
Year after year more sediment falls
on top, creating new layers.
The weight of the layers further
compacts the sediments, squeezing
them tightly together.
The layers often remain visible in
the sedimentary rock.
Sedimentary Rocks: Cementation
While compaction is taking place, the minerals in
the rock slowly dissolve in the water.
The dissolved minerals seep into the spaces
between particles of sediment.
Cementation is the process in which dissolved
minerals crystallize and glue particles of sediment
together.
It often takes millions of years for compaction and
cementation to transform loose sediments into solid
sedimentary rock.
Sedimentary Transformations
Point A: water or wind deposits sediments
Point B: The heavy sediments press down on
the layers beneath
Point C: Dissolved minerals flow between the
particles and cement them together
Metamorphic Rock Pictures
Granite, Gneiss, Shale, Slate, Sandstone, and Quartzite are good
examples of metamorphic rocks.
Bet Cha’ Weren’t Expecting A….
POP QUIZ!!!!!*
1. What are the three types of rock?
2. Which type of rock has been formed by
magma or lava?
3. What do we classify rocks by?
4. How do sedimentary rocks form (in order)?
5. Metamorphic rocks are rocks that have
?(fill in the blank)
6. What is the process of sediments forming a
sedimentary rock?
7. What does “ignis” mean in the word igneous?
*Answers are on next slide!
ANSWERS!!!!
1.
2.
3.
4.
5.
6.
7.
Igneous, Sedimentary, and Metamorphic
Igneous
Texture, Color, and Mineral Composition
Erosion, Deposition, Compaction, Cementation
Morphed
Lithification
“ignis” means fire
www.dlese.com
Earth Science Textbook
Google Images ( I KNOW THIS DOESN’T COUNT IM JUST
TELLING YOU!!)
http://www.rocksandminerals.com/rockcycle.htm
Sedimentary rocks form from
particles deposited by water
and wind
If you have ever walked along a
beach (which I am sure you
have) you may have noticed
tiny sand grains, mud, and
pebbles.
These are some sediments that
eventually form into
sedimentary rocks
Sedimentary Rocks can form in
4 ways by:
Erosion
Deposition
Compaction
Cementation