Transcript minerals - WJHS Team 7A

Mineral Observations
• Examine each mineral on your tray.
– Use the hand lens and magnets (they are below
the sponge on the board)
• List as many characteristics as possible that
could be used to distinguish each mineral.
– What makes each mineral a mineral?
– What makes each mineral unique?
The Characteristics of Minerals
Credits:
Prentice Hall “Science Explorer”
McDougal Littell “Earth Science”
Minerals
• You use minerals all the time. Every time you
turn on a microwave oven or a television, you
rely on minerals. The copper in the wires that
carry electricity to the device is a mineral.
Table salt, or halite, is another mineral you use
in your everyday life.
Minerals
• Minerals are a substance that
– Form in nature
– Are solid
– Have a definite chemical makeup
– Have a crystal structure
– Are inorganic
Minerals
• Some people assume that rocks and minerals
are the same thing. But, a mineral must have
the five characteristics listed above, and rocks
only have two of the characteristics, solid and
form naturally. A rock usually contains two or
more types of minerals.
Minerals
• Two samples of the same type of rock may
vary greatly in the amounts of different
minerals they contain. Minerals, however, are
always made up of the same materials in the
same proportions.
• For example, a ruby is a mineral. A ruby found
in India has the same makeup as a ruby in
Australia.
Check Your Notes
• How are minerals different from rocks?
– Rocks have only two of the five characteristics of
rocks. Rocks are solid and form naturally, but
they are not inorganic, they don’t have a definite
chemical makeup, and they don’t have a crystal
structure.
Formed in Nature
• Natural processes form minerals. Every type
of mineral can form in nature by processes
that do not involve living organisms. Cement,
brick, steel, and glass all come from
substances found in Earth’s crust, but people
manufacture them. Because they don’t occur
naturally in their “finished” state, they are not
considered to be minerals.
Inorganic
• A mineral must also be inorganic. This means
that it can’t come from things that were once
living. Take coal, for instance. Coal occurs
naturally in the crust, but it isn’t a mineral
because it forms from the ancient remains of
plants and animals.
Solid
• A mineral is a solid, which means that it has a
definite volume and rigid shape. If a
substance is a liquid and a gas, it cannot be a
mineral. For example, liquid water is not a
mineral, but ice is.
Check Your Notes
• Why isn’t steel considered a mineral?
– Steel is manufactured by people. To be
considered a mineral, it has to occur naturally in
Earth’s Crust.
• Critical Thinking: Sugar and Salt are things we
use everyday. Are they both minerals? Why
or why not?
– Sugar is not a mineral because it is organic,
meaning it comes from living things.
Definite Chemical Makeup
• Each mineral has a definite chemical makeup: it
consists of a specific combination of atoms of certain
elements. Almost all minerals are compounds. In a
compound, two or more elements are combined so
that the elements no longer have distinct properties.
Each compound has its own properties, which typically
differ greatly from the properties of the elements that
originally formed it.
• Some elements occur naturally in pure form, and not
as part of a compound. These elements, such as
copper, silver, and gold are considered to be minerals.
Almost all pure elements are metals.
Crystal Structure
• Crystals BrainPop
• If you look closely at the particles of ice that
make up frost, you will notice that they have
smooth, flat surfaces. These flat surfaces form
because of the arrangement of atoms in the ice,
which is a mineral. Such an internal arrangement
is a characteristic of minerals. It is the structure
of a crystal, a solid in which the atoms are
arranged in an orderly, repeating, threedimensional pattern.
Crystal Structure
• Each mineral has its own type of crystal structure.
In some cases, two minerals have the same
chemical composition but different crystal
structures.
• For example, both diamond and graphite are
made up of the same element, carbon. But the
arrangements of the carbon atoms in these two
minerals are not the same, so they have different
chemical structures and very different properties.
Diamonds are extremely hard and have a brilliant
sparkle, but graphite is soft, gray, and dull.
Check Your Notes
What is a compound?
Two or more elements are combined so that the
elements no longer have distinct properties.
Critical Thinking: What are the characteristics of
ice that make it a mineral?
It forms in nature, is inorganic, is a solid, has a definite
chemical make-up, and has a crystal structure.