Download Grade Levels: 3 What are rocks made out of? Children will explore

Rocks and Minerals Background
Information for Parents
Grade Levels: 3
What are rocks made out of? Children will explore rocks, and learn how to
describe rocks by its properties, like color, luster, texture, and hardness.
Children will also find out how geologists and other scientists study rocks
to learn about Earth and what our planet was like long ago.
Rocks and minerals are all around us. Earth’s crust and part of its mantle
are made of rock. Rocks are made of minerals and have different
properties, meaning different characteristics or traits. The properties of
rocks include color, texture, luster, and hardness. We use rocks and
minerals in many different ways. The steel in our buildings are made with
iron, which is a mineral. The clay and glass used in our pottery and dishes
are made of a mixture of rocks and minerals. We even need minerals to
stay healthy, and we get them from a variety of different foods. A geologist
is a scientist who studies rocks and land to learn about Earth and its
history. Your children can practice being geologists by observing and
comparing different rocks.
Rock is a natural, nonliving aggregate of minerals. Earth’s outer sections,
or lithosphere, include the crust and part of the mantle, which are made of
rock. The crust of the Earth is made of two categories of rocks: basaltic
and granitic. Basaltic rock is beneath the seafloor, and our continents
consist of granitic rock. The mantle is beneath the crust, and is a thick
layer of hot, solid rock made of magnesium, silicon, iron and oxygen. The
mantle comprises about two-thirds of the Earth’s bulk. Geologists are
scientists who study rocks and land to learn about Earth and its history.
Rocks provide clues about what Earth looked like millions of years ago.
Encourage your children to observe rocks in different ways.
Rocks are made of minerals. Some rocks, such as granite, are comprised
of several minerals, including quartz, feldspar, and mica. Other rocks, such
as gold or silver, are made of only one mineral. Geologists observe the
properties, or traits, of rocks to help them understand, identify, and
categorize them. For example, color is a property. Some rocks like shale or
obsidian are dark gray or black. Other rocks, like quartz, come in a range
of colors like white, pink, or yellow. Texture is a property that describes
how an object feels. Some rocks are smooth, such as those found in rivers
or at the beach, while other rocks are rough and bumpy, such as those
found at the base of a mountain. Luster describes how an object looks
under light. Some rocks are shiny and metallic, such as gold or pyrite.
Other rocks are duller in tone, and not as reflective. Hardness is another
property of rocks. The hardest mineral is diamond, and the only thing that
can cut a diamond is another diamond. The softest mineral is talc, which
can be scratched by a fingernail and ground into fine grains, as in talcum
powder.
We use rocks and minerals in many different ways. Encourage your
children to think about how they use rocks and where they find them. The
steel used to construct buildings is made of iron, which is a mineral. The
counters in their kitchens may be made of granite, which is a rock. Bricks
are made by blending and compressing rocks and minerals, usually sand,
clay, and limestone. Our sidewalks are made of concrete, which is a
mixture of crushed rocks and limestone. Clay pottery, porcelain dishes,
and glasses are all made from rocks and minerals, too. People and
animals get minerals from the foods they eat. Calcium and phosphorus,
minerals found in milk and dark greens, help us build strong and healthy
bones. Many fruits and vegetables are good sources of potassium,
magnesium, and other minerals that our bodies need. Even salt is a
combination of minerals.
Encourage children to see rocks in a whole new light. Remind them that
the Stone Age earned its name because our ancestors used stones for
tools, lived in caves, and utilized rocks for fire pits. Today, rocks provide us
with sidewalks and buildings, and also give us sand, glass, and mirrors. In
addition, minerals are essential for healthy bodies. Rocks are a natural
resource, something from nature that people use and value. How do
people use rocks everyday? How would the world change if we did not
have rocks? Discuss the importance of this natural resource with your
children.