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Study Guide
Minerals of Earth’s Crust
Main Idea
Earth’s crust contains many types of minerals with important
uses.
How Can You Identify a Mineral?
mineral- a solid material of the Earth’s crust.

Minerals are made up of elements
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Some minerals are made from 1 element like gold, silver, copper,
carbon

Most minerals are made from 2 or more elements. These are called
chemical compounds

Scientists classify minerals by looking at the elements they are
made from
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Minerals form into mixed patterns.
o The patterns then form into geometric shapes called
crystals
o 6 types of crystal shapes

Hexagonal, Tetragonal, Cubic, Orthorhombic,
Monoclinic, Triclinic
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Properties used to identify minerals
o Color-The first thing you see on a mineral
o Luster- the way light bounces off a mineral
o Streak- the color powder left when rubbed
o Hardness- measure of how a mineral resists scratching
o Cleavage- the way a mineral breaks along flat surfaces
o Fracture-when a mineral breaks in a jagged way
How do minerals form?
o When hot liquid rock (magma) cools and hardens into a solid.
o When magma cools its molecules slow down and get closer
together
o They come together and form crystals
o The longer it takes, the larger the crystal will grow
o The cooling of hot water
o Water heated by magma has more dissolved minerals
o When water is cooled the water can only hold small amounts of
dissolved minerals
o These minerals then come together to form crystals and fall to
the bottom of the water
o Evaporation
o Ocean water has many dissolved substances
o When water evaporates the leftover dissolved substances form
crystals
What are minerals used for?
o Ores- mineral that have useful substances
o Iron- comes from mineral hematite
o Used to make nails, buildings and ships
o Aluminum- comes from mineral bauxite
o Used for soda cans, pie tins, foil wrap
o
Metals- group of elements found in the ground that conducts heat
and electricity
o
Gems- minerals that are valued for being rare and beautiful
o Examples- diamonds, rubies and sapphires
Earth’s Rocks and Soil
Main Idea
Rocks can be classified according to their composition and
properties.
How are Rocks different and alike?
Rock- a naturally formed solid in the crust made up of 1 or more
minerals
Ways to identify a rock
o name the minerals it has
o look for color, density or texture
o Texture- size, shape and arrangement of mineral crystals
Rocks are grouped into three types according to how they are formed
o Igneous
o Sedimentary
o Metamorphic
Igneous Rocks- formed when melted rock materials cool and harden
o when lava is exposed to the air above ground it hardens and cools
forming igneous rocks
o lava- magma that reaches the surface
o when magma is below the ground it cools slowly and crystals take
longer to grow. This makes the crystals larger
o when magma is above ground cooling is quicker. This makes the
crystals smaller
Sedimentary Rocks- are made of small bits of matter
o Formed when sediments are pushed together. The weight from
each layer of sediments on top of each other squeezes them
together to form the rock
o Examples- halite, shale, siltstone, sandstone, conglomerate
How are sedimentary rocks useful?
o Sandstone- used for buildings
o Limestone- ground up to make concrete
o Bituminous- black coal
Contain fossils
o Fossils- the remains or imprints of living things of the past.
o Examples-footprints in soft mud, plants imprints in rocks
Metamorphic Rocks- a rock formed under heat and pressure from
another kind of rock
How does the rock change or form?
The original rock DOES NOT melt under the heat or pressure instead the
mineral grains in the original rock…
1. flattens and lines up
2. change with substances in surrounding mineral
3. separate into layers of different densities
In each case the result (final product) is DIFFERENT from the original.
How are Metamorphic Rocks used?
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Slate- used for shingles (on roof tops) and stone walkways
o The minerals are tightly packed together so water does not
get through
o Marble- used for statues, floors, countertops
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The minerals have beautiful colors

Easy to carve