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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

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

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

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