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, three-dimensional 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.