Minerals CH 2 Prentice Hall p. 142 CH 2 Prentice Hall p. 142.

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MineralsMineralsCH 2 Prentice Hall

p. 142CH 2 Prentice Hall

p. 142

What is a Mineral?• A naturally occurring,

inorganic solid that has a crystal structure and definite chemical composition.– Over 3,000– 20 minerals form

Earth’s crust.• Rock forming minerals.

Naturally Occurring

• Must form through Earth’s geologic processes.– Cement, Brick, Steel

and Glass all come from substances in Earth’s crust.

– But they are manufactured by people.

• Cannot come from materials that were once part of living things.– Coal- forms naturally,

comes from the remains of plants and animals.

Inorganic

• Always solid, with a definite volume and shape.– Particles can’t flow

freely.

Crystal Structure• Particles of a mineral line up in a repeating

pattern. Forms a solid called a crystal.– Has flat sides called faces, that meet at sharp

edges and corners.

• A mineral always contains certain elements in definite proportions.

• Element- a substance composed of a single kind of atom.– All atoms of the same element have the same

chemical and physical properties.

Definite Chemical Composition

• Compound- Two or more elements combined.– Most minerals are compounds.– Chemically joined.

• You can tell a compound by its chemical name like: NaCl for salt, CO2 for carbon dioxide

Definite Chemical Composition

• Mixture- consists of two or more substances that are mixed together but not chemically combined. (They can be sorted or seperated easily)

Identifying Minerals

Crystal Systems

Cleavage/Fracture

Special Properties

Density

Hardness

Streak

Luster

• 1. Color is an easily observed physical property. Not the best property to use to identify because many minerals like quartz can come in a variety of colors.

Streak

• Streak is the color of the minerals powder when it is rubbed against a Streak Plate – This property does not vary like the color of

the mineral can.

Luster

• Metallic luster- looks like a metal.

• Non-Metallic Luster- does not look like a metal, can be glassy, dull, earthy, waxy and pearly.

• Luster is used to describe how a mineral reflects light from its surface.

Crystal Structure

• Each mineral grows atom to atom to form that mineral’s particular structure.– Classified into six groups (crystal systems) based

on the number and angle of the crystal faces.

5. Cleavage

• Cleavage- is a mineral that easily splits along flat surfaces.

6 Fracture

• Fracture- describes how a mineral looks when it breaks apart in an irregular way.

Special Properties

• Fluorescence- glows under UV (ultraviolet light)

• Magnetic- acts like a magnet• Radioactive- give off radiation- Uraninite• Reacts to Acid- reacts by fizzing.• Electrical Properties- electric current can be

produced (Quartz)– Used in watches

• It is the mass in a given volume.

• It always remains the same for any given mineral.

Density

• A balance would be used to measure the mass of a sample.

• The sample can be placed in a graduated cylinder to determine the volume.

Density

• Water Displacement (how much water is moved, is equal to the volume of the sample) is used to determine the volume of the sample

Density

• One of the best clues.• Mohs hardness scale.

– A scale from 1 to 10.

Hardness

Mohs Hardness Scale

Hardest known mineral, Diamond can scratch all

other surfaces.Identifying Minerals

Minerals CH 2 Prentice Hall p. 142 CH 2 Prentice Hall p. 142.

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