Minerals Pt.2 (L5)

Question 1

The appearance and physical behaviour of minerals are directly related to _______

Answer 1

their chemical composition and bonding characteristics of their components (informative

Question 2

Do all minerals have the same exact set of properties? Y or N

Answer 2

No

Question 3

What is crystal habit?

Answer 3

refers to the external geometric shape of mineral crystals

Question 4

What is cleavage?

Answer 4

It is used for mineral identification

it is the breakage of a mineral along flat, well-defined planes. Occurs in minerals that have bonds of diff strengths

Question 5

What does cleavage refer to?

Answer 5

refers to how a mineral crystal breaks, NOT its external crystal form

Cleavage is a manifestation of the internal structure of mineral crystals

Question 6

What is the simplest case of cleavage? And what can it be used for?

Answer 6

Mica - breaks in one direction

breaks into tiny little flakes that reflect light very well so commonly used as cosmetic glitter

Question 7

Which way will cleavage break?

Answer 7

in the direction of weaker bonding

may be more than one direction of weaker bonding

Question 8

Basal Cleavage

Answer 8

Cleavage in one direction

Question 9

Cubic Cleavage

Answer 9

3 directions at 90 degrees

Question 10

rhombohedral cleaveage

Answer 10

3 directions not at 90 degrees

Question 11

Octahedral cleavage

Answer 11

four directions at 90 degrees to form a 3d shape with 8 sides

Question 12

Why are cleavage planes always surfaces of breakage and don’t follow the same direction as the crystal faces?

Answer 12

Because cleavage is an internal property (breakage along planes of weakness) while the crystal faces is an external property

Question 13

Why do not all minerals show cleavage?

Answer 13

b/c in some minerals, the bonds are relatively uniform in strength, so don’t break along specific planes

Question 14

Fracture

Answer 14

The appearance of a broken surface that isn’t cleavage

Question 15

what is the easiest type of fracture to recognize?

Answer 15

Conchoidal fracture

named b/c of the arc-shaped patterns on the surface that resemble the inside of a seashell

Question 16

Hardness

Answer 16

Another useful diagnostic property

measure of the resistance of minerals to abrasion or scratching

Question 17

what does the hardness of a mineral reflect?

Answer 17

the overall strength of bonding within its crystal structure

stronger bond = greater hardness

Question 18

How is hardness measured

Answer 18

Mohs scale of hardness

Question 19

How do you use Moh’s original hardness scale

Answer 19

we can test it against minerals or other objects of known hardness

Higher hardness will scratch mineral with lower hardness

Question 20

What is Specific Gravity

Answer 20

a number representing the ratio of the weight of a mineral to the weight of an equal volume of water

or we can just say that some minerals are heavier than others

Question 21

Diaphaneity

Answer 21

the ability of a mineral to transmit light

Question 22

3 types the Diaphaneity

Answer 22

transparent, translucent, or opaque

Question 23

Transparent Minerals

Answer 23

transmit light in an undisturbed fashion, like clear glass

Question 24

Transculent Minerals

Answer 24

the light entering the mineral is scattered as it is transmitted (can’t see the details of whatever is on the other side)

Question 25

Opaque

Answer 25

it means that no light is transmitted through the material

Question 26

Why is transclucency tricky to recognize?

Answer 26

b/c it is between transparency and opaque

Question 27

Lustre

Answer 27

the ability of a mineral to reflect light from its surface

Question 28

how is Lustre diff from diaphaneity?

Answer 28

Lustre doesn’t deal with the transmission of light but more on the surface reflection

Question 29

Lustre can be either __ or __

Answer 29

metallic or nonmetallic

Question 30

Colour

Answer 30

manifests the chemical content of a mineral

color can be a very diagnostic property

Question 31

Why can colour sometimes be misleading? Example?

Answer 31

minor impurities or crystal defects can impart strikingly diff colors

Tourmaline (ex): depending on the metals present in this mineral, the color can vary significantly, sometimes even within the same crystal

Question 32

Powder

Answer 32

Another way of identifying some minerals

we do this by rubbing the mineral specimen against an unglazed porcelain plate called a streak plate

Question 33

the streak of hematite is always a ____ colour

Answer 33

reddish brown

Question 34

magnetism

Answer 34

very diagnostic, although limited to only a few minerals

Question 35

If a mineral fizzes which mineral is it most likely to be?

Answer 35

Limestone (used in TUMS)

Question 36

Strange optical properties

Answer 36

some minerals will produce a double image when an object is viewed through its crystals

Question 37

Birefringence

Answer 37

due to the splitting of light rays as they pass through the calcite crystal

Question 38

Most minerals can be identified on the basis of __?

Answer 38

a unique combination of physical properties

Question 39

Sphalerite (ZnS) unique property?

Answer 39

smell of rotten eggs when rubbed

Question 40

Unique property of Graphite?

Answer 40

greasy lustre, is opaque, very soft

Question 41

Unique property of Halite?

Answer 41

tastes salty

Question 42

Unique property of Talc?

Answer 42

Slippery or soapy (used in baby powder)