Minerals

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Minerals
A. What is a mineral?
Mineral Characteristics
shared by all minerals:

1. Natural
– occurs naturally
– NOT manmade
What is a mineral?
1. Natural
 2. Inorganic

– Is not alive
– Was never alive
What is a mineral?
1. Natural
 2. Inorganic
 3. Crystalline

– Atoms are
arranged in an
orderly pattern
What is a mineral?
1. Natural
 2. Inorganic
 3. Crystalline
 4. Definite chemical
composition

– Chemical formula
– SiO2 is Quartz
What is a mineral?
1. Natural
 2. Inorganic
 3. Crystalline
 4. Definite chemical composition
 5. Solid

– Not a gas, not a liquid
How will we remember this?
Natural
 Inorganic
 Crystalline
 Definite chemical composition
 Solid

Mineral Characteristics shared
by all minerals:
Now I Can Define mineralS!
Natural
 Inorganic
 Crystalline
 Definite chemical composition
 Solid

B. Physical Properties of Minerals

1. Color
– First impression
– Not very reliable because lots of minerals
can occur in many different colors
Quartz

Purple Amethyst
Fluorite
•Clear
•Blue
•Green
•Purple
Physical Properties of Minerals
1. Color
 2. Streak

– The TRUE color of a mineral
– Color of a mineral’s powder
Physical Properties of Minerals
1. Color
 2. Streak
 3. Hardness
 4. Cleavage
 5. Fracture
 6. Luster

– How light shines off a mineral
– Metallic or Nonmetallic
Physical Properties of Minerals:
Used for Identification (I.D.)
Color
 Streak
 Hardness
 Cleavage
 Fracture
 Luster

3 types of rocks
3 types of rocks

There are 3 types of
rocks found on
Earth:
– Igneous
– Sedimentary
– Metamorphic

Knowing the
differences between
these 3 types of
rocks allows us to
learn about Earth’s
Igneous Rocks - Formation

Igneous Rocks are
formed by melting,
cooling, and
crystallization of
other rocks.
 Igneous rocks form
as a result of
volcanic activity,
hot spots, and
melting that
occurs in the
Igneous Rocks - Classification

Igneous rocks are
classified using their
texture in the following
ways:
– Glassy
– Aphanitic (no visible
crystals)
– Phaneritic (visible crystals)
– Porphyritic (Some visible
and some not visible
crystals)
Types of Igneous Rock
Intrusive- Forming a large crystals that
the magmas cools down very slowly
Ex. Granite
 Extrusive- they form an amorphous
glass
Ex. Basalt

Sedimentary Rocks - Formation

Sedimentary rocks
are formed by
weathering,
erosion,
deposition,
compaction, and
cementation of
other rocks.
 Sedimentary rocks
form in areas where
water, wind, or
Sedimentary rocks - formation

Sedimentary rocks
are likely to form in
areas such as:
–
–
–
–
–
–
–
Deltas
Beaches
Rivers
Glaciers
Sand dunes
Shallow seas
Deep oceans

Sedimentary rocks Classification
Sedimentary rocks
are classified into two
groups:
– Clastic rocks
– Chemically formed
rocks
Sedimentary rocks –
Classification

Sedimentary rocks
are Clastic if they
are made of pieces
of other rocks that
have been
weathered and
eroded.
 Clastic rocks are
grouped based on
the size of grain that
they are made from.
Sedimentary rocks Classification

Very small particles
make up mudrock.
 Medium sized
particles make up
sandstone.
 Large particles
make up
conglomerates.
Sedimentary rocks Classification

Sedimentary rocks
that form from
chemical processes
are called
biochemical rocks
(formed from living
things) or Chemical
precipitates
(formed from lakes
or shallow seas.)
Sedimentary rocks - formations

Structures and
formations seen in
sedimentary rocks
include:
–
–
–
–
–
–
Stratification
Cross bedding
Graded bedding
Ripple marks
Mud cracks
Fossils
Sedimentary rocks - Examples

Some of the most
common types of
sedimentary rocks
include:
–
–
–
–
–
–
–
Conglomerate
Sandstone
Shale
Limestone
Gypsum
Oolites
Chert (including black
flint and red jasper)
Metamorphic rocks - Formation

Metamorphic rocks
are formed by heat
and pressure
changing one type of
rock into another type
of rock.
 Metamorphic rocks
form near lava
intrusions, at plate
subduction zones,
and in deep
mountain roots.
Metamorphic rocks Classification

Metamorphic rocks
are classified into 2
major groups:
– Foliated
– Nonfoliated
Metamorphic rocks Classification

Foliated rocks form
when differential
pressure causes
minerals to form in
layers.
 These rocks will have
stripes or planes that
they will break easily
along.
 These “stripes” don’t
usually line up with the
original bedding planes
Metamorphic rocks

Nonfoliated
metamorphic rocks
formed in areas
where the pressure
from all sides was
equal, so there is no
“linear” quality to the
rocks.
Metamorphic rocks - Formations

Structures and
formations seen in
metamorphic rocks
include:
–
–
–
–
Folding
Plastic deformation
Stretching
Alternating dark and
light layers (gneissic
foliation)
Metamorphic rocks - Examples

Some common
types of
metamorphic rock
include:
–
–
–
–
–
–
–
Slate
Schist
Gneiss
Amphibolite
Marble
Quartzite
Metaconglomerate
Metamorphic rocks - story

What do you know
about the history of
the Earth in the
place where this
rock was found?
FAULTS
Deformation is the bending, tilting, and breaking
of the Earth’s crust. Plate tectonics is the major
cause of crustal deformation.
When the hanging wall moves down it is
called a normal fault. Normal faults occur
in places where there is tension or the rocks
are being pulled apart.
When the hanging wall moves up it is called
a reverse fault. Reverse faults are caused
by compressional forces.
A low angle reverse fault is called a thrust
fault because one side is being thrust onto
the other.
The last type of faults are called strike-slip
faults. Strike-slip faults slide horizontally
past one another.
Plate tectonics
Plates are driven by cooling of Earth (convection)
Gravity provides additional force to move plates.
?
?
?
Modified from USGS Graphics
Convection is like a boiling pot. Heated soup rises to the surface, spreads and begins to
cool, and then sinks back to the bottom of the pot where it is reheated and rises again.
What are the tectonic plates?
AKA: Lithospheric plate

The ~100-km-thick surface of the Earth;

Contains crust and part of the upper mantle;

It is rigid and brittle;
Fractures to produce earthquakes.

USGS Graphics
What is the asthenosphere?
Asthenosphere:



Is the hotter upper mantle below the lithospheric
plate;
Can flow like silly putty; and
Is a viscoelastic solid, NOT liquid!!
Three Basic Types of Plate Boundaries
Divergent
Using hands to show relative motion
Transform
Convergent
USGS Graphics
Seafloor Spreading
Source: http://www.tectonics.caltech.edu/outreach/animations/index.html
Weathering

Weathering is simply the chemical
and/or physical breakdown of a rock
material--weathering involves specific
processes acting on rock materials at or
near the surface of the Earth
Weathering
In other rocks, minerals may slowly
dissolve.
 Eventually the surface of ALL rocks
crumbles, or weathers.

Types of Weathering

Physical Weathering( mechanical)
– Takes place when rock is split or broken
into smaller pieces of the same material
without changing its composition.
Example: Breaking of a rock cliff into
boulders and pebbles
Types of Weathering

Chemical (decomposition)
– takes place when the rock’s minerals are changed
into different substances.
– Water and water vapor are important agents of
chemical weathering.
Example: Formation of clay minerals from
feldspar
QUIZ #2
Identify what is being described.
1. simply the chemical and/or physical breakdown of a rock material
2. Rocks that are formed by melting, cooling, and crystallization of other
rocks.
3. Rocks that are formed by heat and pressure
Types of weather when the rock’s minerals are changed into different
substances.
5. takes place when the rock’s minerals are changed into different
substances.
6- 10- What are the characteristics of Minerals?
4.
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