MineralsMineralsCH 2 Prentice Hall

p. 47-54CH 2 Prentice Hall

p. 47-54

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 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.

Solid

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 have the same chemical and physical

properties.

Definite Chemical Composition

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

Definite Chemical Composition

Definite Chemical Composition

• Mixture- consists of two or more substances that are mixed together but not chemically combined.

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.

Identifying Minerals

Identifying Minerals

Crystal Systems

Cleavage/Fracture

Special Properties

Density

Hardness

Color

Streak

Luster

Color

• 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.

Identifying Minerals

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.

Identifying Minerals

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.

Identifying Minerals

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.

Identifying Minerals

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.

5. Cleavage

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

Identifying Minerals

6 Fracture

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

Identifying Minerals

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

Identifying Minerals

• The resistance to being scratched. One of the best clues.• Mohs hardness scale.

– A scale from 1 to 10.

Hardness

Identifying Minerals

ss

Mohs Hardness Scale see p150 to label boxes with minerals

Hardest known mineral, Diamond can scratch all

other surfaces.Identifying Minerals

• It is the mass in a given volume.

• It always remains the same for any given mineral.

Density

Identifying Minerals

• 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

Identifying Minerals

• 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

Identifying Minerals