Objectives• Classify minerals according to their physical and

chemical properties.

• Identify different types of minerals.

– luster

– streak

– hardness

– cleavage

– fracture

Vocabulary

Identifying Minerals

Mineral Identification• Geologists rely on several relatively simple tests

to identify minerals.

– Physical properties– Chemical properties.

Identifying Minerals

• It is usually best to use a combination of tests.

Mineral IdentificationColor

Identifying Minerals

– Noticeable characteristic.

– Can be caused by the presence of trace elements.

– Least reliable clue to a mineral’s identity.

Mineral IdentificationLuster

Identifying Minerals

– Luster is the way that a mineral reflects light from its surface.

– metallic or nonmetallic.

Mineral IdentificationTexture

Identifying Minerals

– Texture describes how a mineral feels to the touch.

– smooth, rough, ragged, greasy, soapy, or glassy.

Mineral IdentificationStreak

Identifying Minerals

– Streak is the color of a mineral when it is broken up and powdered.

– Sometimes, a mineral’s streak does not match the mineral’s external color.

– A mineral’s streak rarely changes.

Mineral Identification

Hardness

Identifying Minerals

– Hardness is one of the most useful and reliable tests for identifying minerals.

– Hardness is a measure of how easily a mineral can be scratched.

– Any mineral with a greater hardness than another mineral will scratch that softer mineral.

Mineral Identification

Hardness

Identifying Minerals

Mineral Identification

Cleavage and Fracture

Identifying Minerals

– Minerals break along planes where atomic bonding

is weak.

– Cleavage is the ability of a mineral to split relatively easily and evenly along one or more flat planes.– Fracture is the ability of minerals to break with arclike, rough, or jagged edges.

Mineral IdentificationCleavage and Fracture

Identifying Minerals

Two more specialty tests…• Magnet

– Magnetite is magnetic

• Hydrochloric acid (HCl)

– Calcite = fizzing– Quartz = no fizzing

Section Assessment

1. Match the following terms with their definitions.

___ streak

___ hardness

___ cleavage

___ fracture

Identifying Minerals

A. the ability to break with arc-like, rough, or jagged edges

B. the ability to split relatively easily along one or more flat planes

C. the color of a mineral when it is broken up and powdered

D. a measure of how easily a mineral can be scratched

C

D

B

A

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