Transcript Minerals and Rocks

Ch 5. Minerals
ES 9A.STUDENTS KNOW THE RESOURCES OF
MAJOR ECONOMIC IMPORTANCE IN
CALIFORNIA AND THEIR RELATION TO
CALIFORNIA’S GEOLOGY.
Characteristics of Minerals
 To be a mineral, a substance must have four
characteristics:
must be inorganic—it cannot be made of or by
living things;
must occur naturally—it cannot be man-made;
must be a crystalline solid;
must have a consistent chemical composition.
Kinds of Minerals
 All minerals can be classified into two main groups
— based on their chemical compositions.
 silicate mineral contains a combination of
silicon and oxygen, may also contain one or more
metals
 Silicate minerals make up 96% of Earth’s crust.
 nonsilicate mineral does not contain
compounds of silicon and oxygen
Make up about 4% of Earth’s crust.
Physical Properties of Minerals
Color
 is unreliable for the identification of minerals.
 can be affected by impurities or by weathering
processes.
Streak
 the color of a mineral in powdered form
 determined by rubbing some of the mineral against
an unglazed ceramic tile called a streak plate.
Luster
 the way in which a mineral reflects light
 metallic luster if it reflects light
 All other minerals have nonmetallic luster.
Ex. glassy, waxy, pearly, brilliant, and earthy.
 Cleavage
 the tendency of a mineral to split along specific
planes of weakness to form smooth, flat surfaces
 Fracture
 the manner in which a mineral breaks along either
curved or irregular surfaces
Physical Properties of Minerals
Hardness
 the ability of a mineral to resist scratching is called
hardness.
 Mohs hardness scale the standard scale against
which the hardness of minerals is rated.
 The strength of the bonds between the atoms that
make up a mineral’s structure determines the
hardness of a mineral.
Ch 6 ROCKS
STUDENTS KNOW HOW TO EXPLAIN THE
PROPERTIES OF ROCKS BASED ON THE
PHYSICAL AND CHEMICAL CONDITIONS IN
WHICH THEY FORMED, INCLUDING PLATE
TECTONIC PROCESSES
Three Major Types of Rock
 Rock: The material that makes up the solid parts of
Earth.
 Rocks are classified based on the processes that
form.
3 Types of Rocks
Igneous rock forms when magma, or molten rock,
cools and hardens.
2. Sedimentary rock forms when sediment deposits
that form when rocks, mineral crystals, and organic
matter have been broken into fragments are
compressed or cemented together.
1.
3. Metamorphic rock forms when existing rock is
altered by changes in temperature, pressure, or by
chemical processes.
Chapter 6
The Rock Cycle
 Geologic forces and processes cause rock to change
from one type to another.
 rock cycle the series of processes in which rock
forms, changes from one form to another, is
destroyed, and forms again by geological processes
Chapter 6
The Formation of Magma
 igneous rock rock that forms when magma cools
and solidifies
 The three factors that affect whether rock melts
include
1) temperature,
2) pressure,
3) the presence of fluids in the rock.
Chapter 6
The Formation of Magma, continued
Partial Melting
 Different minerals have different melting points
 As the temperature increases and as other minerals melt,
the magma’s composition changes.
Chapter 6
The Formation of Magma, continued
Fractional Crystallization
 The crystallization and removal of different
minerals from the cooling magma.
 Minerals that have the highest freezing points
crystallize first.
Chapter 6
Textures of Igneous Rocks
 intrusive igneous rock rock formed beneath Earth’s
surface
 extrusive igneous rock rock formed at Earth’s surface
Chapter 6
Textures of Igneous Rocks, continued
Coarse-Grained Igneous Rock
 Because intrusive igneous rocks cool slowly, they
commonly have large mineral crystals.
Fine-Grained Igneous Rock
 Because extrusive igneous rocks cool rapidly, they are
commonly composed of small mineral grains.
Sedimentary Rock
Rocks, mineral crystals, and organic matter that
have been broken into fragments .
2. Sediment is carried away and deposited by water,
ice, and wind.
3. Sediment deposits are compressed or cemented
together and harden they form sedimentary rock.
1.
Chapter 6
Section 3 Sedimentary Rock
Chemical Sedimentary Rock
 chemical sedimentary rock sedimentary rock
that forms when minerals precipitate from a
solution or settle from a suspension
Chapter 6
Section 3 Sedimentary Rock
Organic Sedimentary Rocks
 organic sedimentary rock sedimentary rock
that forms from the remains of plants or animals
Chapter 6
Section 3 Sedimentary Rock
Organic Sedimentary Rocks,
continued
The diagram below shows the formation of organic limestone.
Chapter 6
Section 3 Sedimentary Rock
Clastic Sedimentary Rock
 clastic sedimentary rock sedimentary rock that forms
when fragments of preexisting rocks are compacted or
cemented together
Chapter 6
Formation of Metamorphic Rocks
 One type of rock changes into metamorphic
rock because of chemical processes or
changes in temperature and pressure
 Heat, pressure, and hot fluids cause
some minerals to change into other
minerals.
Chapter
6 of Metamorphic Rocks,
Formation
continued
Contact Metamorphism
 A change in the texture, structure, or chemical
composition of a rock due to contact with magma
Regional Metamorphism
 A change in the texture, structure, or chemical
composition of a rock due to changes in
temperature and pressure over a large area,
generally are a result of tectonic forces
Chapter 6
Classification of Metamorphic Rocks
Foliated Rocks
 Minerals grains are arranged in planes or bands
 Extreme pressure may cause the mineral crystals
in the rock to realign or regrow to form parallel
bands.
Chapter 6
Classification
of Metamorphic Rocks,
continued
Nonfoliated Rocks
 Minerals grains are not arranged in planes or
bands