Minerals Pt.2 (L5) Flashcards

1
Q

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

A

their chemical composition and bonding characteristics of their components (informative

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2
Q

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

A

No

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3
Q

What is crystal habit?

A

refers to the external geometric shape of mineral crystals

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4
Q

What is cleavage?

A

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

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5
Q

What does cleavage refer to?

A

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

Cleavage is a manifestation of the internal structure of mineral crystals

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6
Q

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

A

Mica - breaks in one direction

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

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7
Q

Which way will cleavage break?

A

in the direction of weaker bonding

may be more than one direction of weaker bonding

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8
Q

Basal Cleavage

A

Cleavage in one direction

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9
Q

Cubic Cleavage

A

3 directions at 90 degrees

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10
Q

rhombohedral cleaveage

A

3 directions not at 90 degrees

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11
Q

Octahedral cleavage

A

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

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12
Q

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

A

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

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13
Q

Why do not all minerals show cleavage?

A

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

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14
Q

Fracture

A

The appearance of a broken surface that isn’t cleavage

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15
Q

what is the easiest type of fracture to recognize?

A

Conchoidal fracture

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

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16
Q

Hardness

A

Another useful diagnostic property

measure of the resistance of minerals to abrasion or scratching

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17
Q

what does the hardness of a mineral reflect?

A

the overall strength of bonding within its crystal structure

stronger bond = greater hardness

18
Q

How is hardness measured

A

Mohs scale of hardness

19
Q

How do you use Moh’s original hardness scale

A

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

Higher hardness will scratch mineral with lower hardness

20
Q

What is Specific Gravity

A

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

21
Q

Diaphaneity

A

the ability of a mineral to transmit light

22
Q

3 types the Diaphaneity

A

transparent, translucent, or opaque

23
Q

Transparent Minerals

A

transmit light in an undisturbed fashion, like clear glass

24
Q

Transculent Minerals

A

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

25
Opaque
it means that no light is transmitted through the material
26
Why is transclucency tricky to recognize?
b/c it is between transparency and opaque
27
Lustre
the ability of a mineral to reflect light from its surface
28
how is Lustre diff from diaphaneity?
Lustre doesn't deal with the transmission of light but more on the surface reflection
29
Lustre can be either __ or __
metallic or nonmetallic
30
Colour
manifests the chemical content of a mineral color can be a very diagnostic property
31
Why can colour sometimes be misleading? Example?
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
32
Powder
Another way of identifying some minerals we do this by rubbing the mineral specimen against an unglazed porcelain plate called a streak plate
33
the streak of hematite is always a ____ colour
reddish brown
34
magnetism
very diagnostic, although limited to only a few minerals
35
If a mineral fizzes which mineral is it most likely to be?
Limestone (used in TUMS)
36
Strange optical properties
some minerals will produce a double image when an object is viewed through its crystals
37
Birefringence
due to the splitting of light rays as they pass through the calcite crystal
38
Most minerals can be identified on the basis of __?
a unique combination of physical properties
39
Sphalerite (ZnS) unique property?
smell of rotten eggs when rubbed
40
Unique property of Graphite?
greasy lustre, is opaque, very soft
41
Unique property of Halite?
tastes salty
42
Unique property of Talc?
Slippery or soapy (used in baby powder)