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5.3IDENTIFYING MINERALS Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals.

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Page 1: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

5.3IDENTIFYING MINERALS

Objectives:

1) What do scientists look for when identifying minerals

2) Describe 3 simple tests scientists use to identify

minerals.

Page 2: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

KEY IDEA Minerals can be identified by physical

and chemical propertiesColorLusterCrystal shapeStreakCleavageFractureHardnessSpecific gravityReaction to an acid

Page 3: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

INTRODUCTION Mineralogy: the

study of minerals and their properties

Many minerals can be identified and classified by Inspecting

visuallyDoing simple

tests to find properties

Page 4: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

ROCK-FORMING MINERALS

Almost 4000 known minerals

About 30 are common Rock-forming minerals: a

specific group of minerals known to form rocks

Rocks are often made of many minerals

Identify a mineral by looking at the physical properties

Tests can identify chemical properties of minerals

Page 5: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

IDENTIFYING MINERALS BY INSPECTION A field guide is

usefulLists properties

Color Luster Crystal shape

Rarely is a mineral identified by a single property

Page 6: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

IDENTIFYING MINERALS BY INSPECTION CONT’D

ColorThe least useful

property for mineral identification Many minerals have

similar colors Impurities can turn

colorless minerals into colored minerals

Some minerals change color in various circumstances

Page 7: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

IDENTIFYING MINERALS BY INSPECTION CONT’D Luster: the way the

mineral shines in light Metallic

Shines like polished metal

Nonmetallic Several categories

Vitreous Pearly Adamantine Greasy Oily Dull Earthy

Page 8: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

TESTING MINERAL SPECIMENS Simple physical

testsStreakCleavageHardnessSpecific gravity

Page 9: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

TESTING MINERAL SPECIMENS CONT’D

Streak: a mineral is the color of its powder Rub the mineral on an unglazed white tile (streak plate) The color of a mineral may vary but the streak rarely does Metallic mineral streak is at least as dark as the specimen Nonmetallic streaks are colorless or white

Page 10: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

TESTING MINERAL SPECIMENS CONT’D

Cleavage: tendency to split easily along flat surfacesUseful b/c surfaces can be observed even on

tiny mineral grains

Page 11: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

TESTING MINERAL SPECIMENS CONT’D

Irregular Fracture

Fracture: when minerals break in directions other than along cleavage surfaces Conchoidal (smooth

and curved) Splintery (jagged

surface w/sharp edges Uneven or irregular

(generally rough surface)

Page 12: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

TESTING MINERAL SPECIMENS CONT’D

Talc

Hardness: resistance to being scratched

Friedrich Mohs made a number scale to determine hardness of a mineral Range of 1-10 Softest-hardest Talc-Diamond 1 limitation

The increase in hardness at each step is not uniform

Page 13: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

TESTING MINERAL SPECIMENS CONT’D Specific gravity: the

ratio of its mass to the mass of an equal volume of water Tells how many times

denser the mineral is than water Density: the ratio

between a substance’s mass and its volume

Nonmetallic minerals have specific gravities less than those of ore minerals and native metals

Page 14: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

TESTING MINERAL SPECIMENS CONT’D

Buoyancy: the tendency of an object to float in water

Archimedes’ Principal: an object will weigh less when it is in water then when it is in air and that this difference is equal to the weight of the displaced water A mineral sample will

displace an amount of water equal to its own volume

Page 15: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

SPECIAL PROPERTIES OF MINERALS Double refraction:

splits light rays that pass through it so 1 object will look like 2 when looking through the specimen

Page 16: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

SPECIAL PROPERTIES OF MINERALS CONT’D

Fluorescent: appearing to glow when viewed under ultraviolet light

Phosphorescent: continue to glow after the ultraviolet light is turned off

Page 17: Objectives: 1) What do scientists look for when identifying minerals 2) Describe 3 simple tests scientists use to identify minerals

5.3 EXIT TICKET Answer the

following questions. Use complete

sentences. You may NOT use

your book. You MAY use your notes.

This is a quiz grade.

1) What do scientists look for when identifying minerals

2) Describe 3 simple tests scientists use to identify minerals.