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Foundations of mineralogy > Lecture three part 1 > Flashcards

Lecture three part 1 Flashcards

1
Q

What are nesosilicates

A

Minerals with isolated SIO4 tetrahedra in the Structure

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2
Q

What compounds are absent in nesosilicates

A

Compounds with alkali elements such as sodium and potassium

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3
Q

What are some Physical properties of nesosilicates And why do they exist

A

Nesosilicates have poorly developed cleavage they are relatively hard and they have higher density than other silicate structure types because their atomic packing is notably dense

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4
Q

What are the two main groups of nesosilicates

A

The olivine group the Garnet group

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5
Q

What type of Silicates are olivines

A

Nesosilicates

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6
Q

What type of silicates are garnets

A

Nesosilicates

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7
Q

What are the four main types of olivine

A

Forsterite, fayalite, tephroite, and Monticellite.

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8
Q

What is peridot

A

Semi-precious gem quality forsterite

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9
Q

What is the chemical composition of forsterite (Fo)

A

Mg2SiO4

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10
Q

What is the chemical composition of Fayalite (Fa)

A

Fe2SiO4

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11
Q

What is the chemical composition of tephroite (te)

A

Mn2SiO4

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12
Q

What is the chemical composition of Monticellite (Mo)

A

CaMgSiO4

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13
Q

What is a solid solution

A

The Ability of one solid end member To dissolve into another with complete miscibility

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14
Q

Between which two end members does Fayalite exist in complete solid solution with

A

Forsterite and tephroite

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15
Q

Can a solid solution exist between forsterite and tephroite

A

No

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16
Q

Can a solid solution exist between monticellite and forsterite

A

No

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17
Q

With what symmetry do the end members of Olivine crystallize

A

Orthorhombic symmetry

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18
Q

What effect does temperature have on interstitial sites

A

It increases them

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19
Q

What effect does temperature have on interstitial sites

A

It decreases them

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20
Q

At what temperature does Forsterite melt

A

1890 degrees

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21
Q

At what temperature does Fayalite melt

A

1200

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22
Q

What is a phase diagram

A

A diagram which displays the changes of phase of a material under related conditions such as temperature vs pressure or temperature vs composition

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23
Q

What is the liquidus line in a phase diagram

A

The line across which a material transitions from a complete liquid to a partial solid /partial liquid

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24
Q

What is the solidus line in phase diagrams

A

The line across which a material transitions from partial liquid/partial solid to completely solid

25
Q

What are the residual liquids during the crystallization process called

A

Restites

26
Q

Under what conditions does olivine undergo serpentinization

A

Hydrothermal events and low temperature

27
Q

What is hydrothermal activity

A

Any process associated with igneous activity involving heated or superheated water

28
Q

What is serpentinization

A

The process whereby weathered olivine alters into serpentine

29
Q

What are the three polymorphs or serpentine

A

Lizardite, crysolite, and antigorite

30
Q

Does serpentine occupy a greater or smaller volume than Olivine

A

A greater volume, it causes olivine to fracture

31
Q

What is the oxidized form of olivine called

A

Iddingsite, though it is now known to consist of haematite and periclase (MgO)

32
Q

What is the mantle transition zone

A

The portion of the mantle between 500 and 670 km which separates the upper from the lower mantle

33
Q

What does Olivine change into in the Transition Zone

A

The more dense Wadsleyite and then to a spinel structure called ringwoodite

34
Q

What is a spinel structure

A

A cubic mg-fe aluminum oxide pseudomorphed with other high density minerals

35
Q

What are the hand specimen properties of Olivine

A

Short prismatic crystals with a hardness of 6-7 and a green colour. It has no streak and a transparent vitreous lustre. It does not usually display cleavage, and it fractures in a conchoidal manner

36
Q

What pleochoism does olivine display.

A

Usually colourless. Darker colours represent higher iron content

37
Q

What is the habit of Olivine

A

Usually anhedral grains in intrusive and metamorphic rocks. Equant or elongated euhedral grains in extrusive volcanic rocks.

38
Q

What is the relief of Olivine

A

High

39
Q

Does Olivine have cleavage

A

Not observed

40
Q

What is the birefringence of olivine

A

0.03 - 0.05 up to third order

41
Q

What is the interference figure of Olivine.

A

Biaxial, positive or negative, 2v = 46 -98

42
Q

What is the extinction of olivine

A

Parallel to crystal outlines

43
Q

Does olivine have twinning

A

Not usually

44
Q

What is the general formula of a garnet

A

X3Y3(SiO4)3

45
Q

What are the 6 common types of garnet

A

Pyrope, Almandine, Spessartine, Grossular, Andradite, Uvarovite

46
Q

What is the most common kind of Garnet

A

Almandine

47
Q

What is the chemical composition of Pyrope (Py)

A

Mg3Al2(SiO4)3

48
Q

What is the chemical composition of Almandine (Al)

A

Fe3Al2(SiO4)3

49
Q

What is the chemical composition of Spessartine (sp)

A

Mn3Al2(SiO4)3

50
Q

What is the chemical composition of Grossular (gr)

A

Ca3Al2(SiO4)3

51
Q

What is the chemical composition of Andradite (An)

A

Ca3Fe2(SiO4)3

52
Q

What is the chemical composition of Uvarovite (Uv)

A

Ca3Cr2(SiO4)3

53
Q

What are pyrope, almandine, and spessartine sometimes referred to as?

A

Pyralspites

54
Q

What are Uvarovite, grossular and andradite sometimes referred to as?

A

Ugrandites

55
Q

What symmetry do garnets crystallize with

A

Cubic symmetry

56
Q

Between what two end members does almandine exist in complete solid solution with

A

Pyrope and Spessartine

57
Q

Is there a complete solid solution between pyrope and spessartine?

A

No only a limited solid solution

58
Q

Do pyralspites and ugrandites exist in solid solution

A

No there is no continuous solid solution between these two groups of Garnet

59
Q

Is there solid solution between the end members of ugrandites

A

Yes extensive solid solution exists between grossular, andradite, and Uvarovite

Foundations of mineralogy (2 decks)

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