Earth’s Surface

Mr. GreathouseChapter 2.2

Color and Streak

COLOR cannot be identified simply by looking at a mineral

Outside appearance can vary due to erosion, bacteria, or other factors.

A streak test must be conducted to tell the color of a mineral

Identifying Minerals

STREAK: The color

left behind after a mineral is scraped across a surface

Streak

Luster: the way the light reflects from a

minerals surface. There are two types of luster:

Metallic (looks like metal) Nonmetallic (doesn’t look like metal)

Luster

Luster

Check for

understanding What is the

difference between streak and luster?

A) There is no difference

B) Streak is how shiny a mineral is, and luster is the mark a mineral leaves behind.

C) Luster is how shiny a mineral is, and streak is the mark a mineral leaves behind

The way a mineral breaks and cracks can help

identify it. Cleavage: is the tendency of a mineral to

break along flat surfaces If minerals break along FLAT surfaces, its atoms

have WEAK bonds

Breaks, Cracks, Fractures

Cleavage

Fracture: the tendency of a mineral to break

into irregular pieces (curves, splinters, rough, jagged). If a mineral breaks into irregular pieces, its

atoms have STRONG bonds. There are 3 main types of fractures

Fracture

Fractures

Conchoidal Fracture: a curved breakage that often occurs in amorphous (without shape) or fine-grained minerals. CAN happen in crystalline as well. Examples: Opal,

Quartz

Fractures

Earthy fracture: is similar to freshly broken soil. Usually seen in soft,

loosely-bound minerals

Fractures

Hackly fractures: jagged, sharp, and uneven. It occurs when metals are torn. Examples: copper,

silver

Check for

understanding What is the

difference between fracture and cleavage?

A) Facture is irregular breaks and Cleavage is flat breaks

B) Cleavage is irregular breaks and Fracture is flat breaks

C) Fractures are always shorter breaks than cleavage

Check for

understanding Which kind of break

has stronger atomic bonds?

A) Cleavage

B) Fracture

C) It is impossible to tell

Density

Density: the amount of mass in a given volume Example:

The amount of g in a mL, or g/mL

The amount of g in a cm3, or g/cm3

When 2 objects have the same mass, the one with the smallest volume is denser

When 2 objects have the same volume, the one with most mass is denser

Same mass- which is

more dense?

Same volume- which

is more dense?

Lets create a tree map with out partner (I need to see BOTH handwritings)

Our tree maps will have 7 ways to identify a mineral, so how many branches should it have?

We have gone over 5 so far, what are they? Streak Luster Cleavage Fracture Density

Include definition and examples of each

Tree Map

Hardness: a minerals resistance to being

sctratched. Something called the Mohs scale is used to

describe a minerals hardness. A harder mineral will scratch a softer mineral. Harder minerals have stronger bonds

Hardness

Mohs ScaleRemember talc from 2.1, and how LeBron throws it into the air?

What is the hardest substance we know of?

Which would scratch which between talc and diamond?

Which are likely to fracture?

Which is likely to cleavage?

Some minerals have special properties

Some minerals show reactivity Other minerals have fluorescence Others display magnetism

Special Properties

Reactivity

Remember from chemistry, some elements and compounds react with each other.

Some minerals react with acid to form bubbles (gas)

Fluorescence

Fluorescence: a property of a mineral allowing it to emit visible light with exposed to UV light, or after being exposed to UV light.

Magnetism

Magnetism: the ability to respond to magnetic force

Iron, nickel, magnetite are magnetic

Finish

Finish the tree map Hardness Special

Reactivity Fluorescence Magnetism

Prepare for lab