Earth’s Resources
Chapter Four
Lesson One:
Minerals & Rocks
Objectives
• Compare and contrast properties of minerals.
• Describe how three main kinds of rocks form.
Read Science books page 202 & do review page 203
Minerals and Rocks Vocabulary: Lesson 1
 Luster- The property of a mineral that describes how light reflects from the mineral.
 Sediment- Tiny bits of animals, plants, or weathered rock.
 Mineral- A solid, nonliving substance found in nature.
 Sedimentary Rock- formed when layers of sediment pile up and are pressed together.
 Metamorphic Rock- Formed deep inside the Earth. Heated and squeezed by the
weight of rocks above.
 Igneous Rock- Formed when melted rock is cooled and hardened either inside Earth
or on Earth’s surface.
What are minerals?
A mineral is a solid, nonliving substance found in nature.
Salt, gold, and iron are minerals.
The graphite in your pencil is a mineral!!!
Minerals are the building blocks of rocks.
Minerals are found underground and in soil. They are even in the ocean and on the
ocean floor. There are more than 3,000 different kinds of minerals. Each mineral has its
own properties. You can use the properties of minerals to tell them apart.
Color
Turquoise
Feldspar
Quartz
It is easy to observe a
mineral’s color. Most
minerals come in just
one color. However,
some, like quartz, come
in many colors. Some,
like gold and pyrite, are
the same color. You
cannot use color alone
to identify a mineral.
Streak
Streak is another property used to identify minerals. Streak is the
color of the powder left when a mineral is rubbed across a white
tile. A mineral’s streak may or may not be the same as the
mineral’s color.
Luster
Luster describes how light bounces off a mineral. Some
minerals are shiny like metal. Others are not. Luster is
another property used to identify a mineral.
Hardness
The hardness of a mineral
describes how easily it can
be scratched. Some
minerals, like talc and
gypsum, are soft. They can
be scratched with a
fingernail. Other minerals,
like quartz, are much harder.
Not even a steel file can
scratch quartz.
Pyrite may look like gold,
but its streak is different.
Pyrite’s streak is greenishblack. Gold’s streak is
yellow.
Mica can have a pearly luster.
Diamond is the hardest mineral.
No other mineral or object can
scratch it.
How can hardness be used to identify minerals?
Mohs’ hardness scale shows the hardness of a few
common minerals. There are many more minerals
for each level of hardness. Diamond, 10 on the
scale, is the hardest mineral. Talc, 1 on the scale,
is one of the softest minerals.
Minerals with higher numbers can scratch
minerals with lower numbers. For example, quartz
can scratch any mineral with a hardness that is
less than 7. Quartz, however, can itself be
scratched by a mineral with a hardness that is
greater than 7.
What are rocks?
A rock is a nonliving material made of one or more
minerals. There are hundreds of different types of
rocks. Some rocks, like granite, are made of several
minerals. Some rocks, like limestone, are made mostly
of one mineral. A rock’s color gives clues about the
minerals that make it up.
Grains
Rocks are made of mineral pieces called grains. To a person who studies
rocks, a rock’s texture is how its grains look. Some rocks have large
grains you can easily see. These rocks have a coarse texture. Some rocks
have grains that are too small to see. These rocks have a fine texture.
Igneous Rocks
Rocks are classified by how they form. There are three kinds of
rocks-igneous, sedimentary, and metamorphic.
An igneous rock forms when melted rock cools and hardens.
Inside Earth, melted rock called magma cools and hardens very
slowly. A rock with large mineral grains forms.
Melted rock that flows onto Earth’s surface is called lava. Lava
cools and hardens quickly. A rock with small mineral grains
forms.
What are sedimentary and metamorphic rocks?
 Sediment is tiny bits of weathered
rock or once-living animals or plants.
 Sedimentary rock is a kind of rock
that forms from layers of sediment.
 Sedimentary rocks form where
weathered and eroded materials are
dropped. This often happens at the
bottom of rivers, lakes, and oceans.
Over time, sediment piles up. The
top layers press on layers below. In
time the sediment becomes
cemented together and forms rock.
What are sedimentary and metamorphic rocks?
 A rock that has been changed by
heating and squeezing is a
metamorphic rock.
 Deep inside Earth, rocks heat up and
“bake.” They also get squeezed by the
weight of the rocks above them. All
this heating and squeezing can cause a
rock’s minerals to change into new
minerals. A new rock forms with
properties that are different from the
original rock.
Shale is a sedimentary rock made
up of bits of weathered materials.
Gneiss is a metamorphic rock. It
forms from granite.
Fossils are often found in the
sedimentary rock limestone. Limestone
can form from the remains of onceliving things.
Slate is a metamorphic rock. It
forms from shale.
Sandstone is sedimentary rock that
forms from tiny particles of sand .
Phyllite is a metamorphic rock. It forms
from the metamorphic rock slate.