8 ch15 rocksmineralmixtures

8th Grade Science

© Fall 2005, Pflugerville ISD, 8th Grade


Chapter 15- Rocks: Mineral
Mixtures
Section 1: From Minerals to Rocks
Section 2: Igneous Rocks
Section 3: Sedimentary Rock
Section 4: Metamorphic Rock
© Fall 2005, Pflugerville ISD, 8th Grade

Unit 3 : Chapter 15


What is a Mineral?
What Do You Think?
What are some items you use in your
everyday life that come from minerals?

© Fall 2005, Pflugerville ISD, 8th Grade

Unit 3 : Chapter 15 : Secti


What is a Mineral?

Halite Crystal (NaCl)

© Fall 2005, Pflugerville ISD, 8th Grade

•All minerals
must meet the
following five
characteristics:
Unit 3 : Chapter 15 : Secti


What is a Mineral?

•Natural,
inorganic solid
that forms a
crystal lattice
and
has
a
Halite Crystal (NaCl)
chemical
formula

© Fall 2005, Pflugerville ISD, 8th Grade

Unit 3 : Chapter 15 : Secti


What is a Mineral?

Halite Crystal (NaCl)

© Fall 2005, Pflugerville ISD, 8th Grade

•Since they form
crystals, all
minerals are
ionic compounds

Unit 3 : Chapter 15 : Secti


Types of Minerals

•Minerals are
grouped by the
chemicals in them
Muscovite
crystal under
microscope
© Fall 2005, Pflugerville ISD, 8th Grade

•Silicate minerals
contain silicon
and oxygen
Unit 3 : Chapter 15 : Secti


Silicate Minerals

Muscovite
crystal under

microscope
© Fall 2005, Pflugerville ISD, 8th Grade

•Over 90% of
the minerals in
Earth’s crust
are silicates
Unit 3 : Chapter 15 : Secti


Nonsilicate Minerals

•Nonsilicates
are minerals
that do not
contain silicon
Calcite (CaCO3)
© Fall 2005, Pflugerville ISD, 8th Grade

Unit 3 : Chapter 15 : Secti


Nonsilicate Minerals

Calcite (CaCO3)
© Fall 2005, Pflugerville ISD, 8th Grade

•Nonsilicates
are made of
elements such

as carbon,
oxygen, iron
and sulfur
Unit 3 : Chapter 15 : Secti


Nonsilicate Minerals

Calcite (CaCO3)
© Fall 2005, Pflugerville ISD, 8th Grade

•Carbonates,
such as calcite,
are used in
cement, building
stone, and
fireworks
Unit 3 : Chapter 15 : Secti


Nonsilicate Minerals

Halite (NaCl)

© Fall 2005, Pflugerville ISD, 8th Grade

•Halide
minerals
are used in
fertilizer, or

to season
your food
Unit 3 : Chapter 15 : Secti


Nonsilicate Minerals

Corundum (Al2O3)
© Fall 2005, Pflugerville ISD, 8th Grade

•Oxide
minerals are
used to make
abrasives and
aircraft parts
Unit 3 : Chapter 15 : Secti


Nonsilicate Minerals

Gypsum (CaSO4•2H2O)

© Fall 2005, Pflugerville ISD, 8th Grade

•Sulfates are
used in
cosmetics,
toothpaste,
and paint
Unit 3 : Chapter 15 : Secti

Identifying Minerals

•Geologists use physical properties
such as color, luster, streak, and
many others to identify minerals
© Fall 2005, Pflugerville ISD, 8th Grade

Unit 3 : Chapter 15 : Secti


Identifying Minerals

•Quartz and
amethyst are both
SiO2, but amethyst
contains impurities
that
give
it
a
purple
Quartz/Amethyst
color
Scepter (SiO )
2

© Fall 2005, Pflugerville ISD, 8th Grade

Unit 3 : Chapter 15 : Secti


Identifying Minerals

•Because a single
mineral can be
many colors, color
is not a reliable
way to identify a
Quartz/Amethyst
mineral
Scepter (SiO )
2

© Fall 2005, Pflugerville ISD, 8th Grade

Unit 3 : Chapter 15 : Secti


Identifying Minerals

Galena (PbS)Metallic Luster
© Fall 2005, Pflugerville ISD, 8th Grade

•The way the
surface of a
mineral
reflects light is
called luster

Unit 3 : Chapter 15 : Secti


Identifying Minerals

•Bauxite, the ore
of aluminum, has
a nonmetallic
luster

Bauxite (Al2O3•2H2O)Earthy Luster
© Fall 2005, Pflugerville ISD, 8th Grade

Unit 3 : Chapter 15 : Secti


Identifying Minerals

•Streak is the
color of a
mineral in
powdered form
© Fall 2005, Pflugerville ISD, 8th Grade

Unit 3 : Chapter 15 : Secti


Identifying Minerals

•Hematite’s

color may
change, but
its streak is
always the
same
© Fall 2005, Pflugerville ISD, 8th Grade

Unit 3 : Chapter 15 : Secti


Identifying Minerals

Cleavage Planes
© Fall 2005, Pflugerville ISD, 8th Grade

•Fluorite,
halite, and
calcite all have
cleavage along
flat planes
Unit 3 : Chapter 15 : Secti


Identifying Minerals

Conchoidal Fracture
© Fall 2005, Pflugerville ISD, 8th Grade

•Sulfur has
conchoidal

fracture,
meaning it
breaks
unevenly
Unit 3 : Chapter 15 : Secti


Identifying Minerals

•A mineral’s
resistance to
scratching it is
called hardness

© Fall 2005, Pflugerville ISD, 8th Grade

Unit 3 : Chapter 15 : Secti


Identifying Minerals

•Hardness is
measured using
Mohs’ hardness
scale

© Fall 2005, Pflugerville ISD, 8th Grade

Unit 3 : Chapter 15 : Secti