Identifying MineralsIdentifying Minerals

Pages 49-54Pages 49-54

Identifying Minerals

Crystal Systems

Cleavage/Fracture

Special Properties

Density

Hardness

Color

Streak

Luster

Color

• 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 mineral’s 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

Cleavage

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

Identifying Minerals

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

• 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

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

– A scale from 1 to 10.

Hardness

Identifying Minerals

Mohs Hardness Scale

Identifying Minerals

Mohs Hardness Scale6.

Hardest known mineral, can scratch all other surfaces.

MineralMineral Hardness RatingHardness Rating

Talc 1Gypsum 2Calcite 3Fluorite 4Apatite 5

Feldspar 6Quartz 7Topaz 8

Corundum 9Diamond 10