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DAY 2 - PETROLOGY AND MINERALOGY > Week 2 > Flashcards

Week 2 Flashcards

1
Q

How is the octahedral form expressed in general form notation?

A

{111}

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1
Q

A mineral aggregate composed of scales or lamellae is described as ________ when it has fine scales with divergent or featherlike structure.

A. Foliated
B. Lammelar
C. Plumose
D. Micaceous

A

C. Plumose

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1
Q

What is the symbol of a form in a particular crystal class that contains faces that intersect all crystallographic axes at different lengths?

A

{hkl}

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1
Q

What term is used to indicate the outward appearance of crystals in crystallography?

A

Habit

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2
Q

What information does the Miller’s indices notation provide about a crystal’s form?

A. Physical properties
B. Atomic arrangement
C. Symmetry class
D. Growth conditions

A

B. Atomic arrangement

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3
Q

It refers to the color of a finely powdered mineral.

A

Streak

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4
Q

How many faces does a cube (isometric crystal form) have?

A

6

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5
Q

It is an imaginary straight line that pass through the center of a crystal, when the crystal rotates around this axis similar face, edge or solid angle appear.

A

Axis of Symmetry

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6
Q

What is the primary function of the Hermann-Mauguin notation in crystallography?

A. Describing habit
B. Identifying symmetry elements
C. Counting faces
D. Classifying chemical properties

A

B. Identifying symmetry elements

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7
Q

How many faces does a tristetrahedron have?

A

12

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8
Q

This is a crystal system where the unit cell is in the shape of a cube.

A

Isometric Crystal System

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9
Q

This crystal system have three axes that are all equal in length and intersect at three different angles ( any angle but 90°).

A

Triclinic

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10
Q

This crystal system have three axes, all at right angles, and all three of different lengths.

A

Orthorhombic

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11
Q

It is a set of crystal faces that completely enclose space.

A

Closed Form

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12
Q

What is the term used to describe a vesicle in a volcanic rock that is filled with secondary minerals?

A

Amygdaloidal

(e.g. calcite)

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13
Q

How are open forms different from closed forms in crystallography?

A

Closed forms enclose space, open forms do not

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14
Q

Differentiate malleable, ductile, and sectile.

A

Malleable - hammered into thin sheets (e.g. native copper, gold)
Ductile - drawn into thin wire (e.g. gold, silver, copper)
Sectile - cut into thin shaving with a knife (e.g. argenite)

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15
Q

The crystal form - dipyramid is described as?

A

Having 6-, 8-, 12-, 16-, or 24-faced closed form in which the lower pyramid is a reflection of the upper.

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16
Q

What are the characteristics of a mineral?

A

N-aturally occuring
I-norganic
D-efinite chemical composition
O-rdered crystal structure
H-omogeneous

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17
Q

Define the term reniform.

A

A crystal habit described as radiating individuals terminating in round kidney-shaped masses.

(e.g. hematite)

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18
Q

What is the Hermann-Mauguin notation used for?

A

Describe the point group symmetry.

19
Q

Describe the term Curie Point.

A

It is the temperature which the mineral loses its magnetism.

(Magnetite -580 deg C)
(Hematite - 680 deg C)

20
Q

What are striations?

A

These are parallel (hairline grooves) sets of linear features that appear as engraved ridges and/or grooves on mineral surfaces.

Ex. tourmaline, quartz

21
Q

In the Mohs Hardness Scale, what minerals can be scratched with fingernails?

A

Talc and Gypsum

22
Q

What is chatoyancy?

A

A play in colors that occurs specifically in fibrous minerals, when a band of light move perpendicular to fibers. (Quartz - cat’s eye; tourmaline)

23
Q

Differentiate idiochromatic and allochromatic.

A

Idiochromatic - “self-colored” or its pure state or color (malachite - green)
Allochromatic - “foreign-colored” due to impurities (quartz)

24
Q

What is the primary characteristic of a pyramid in crystallography?

A

Faces meeting in a point

25
Q

The closed crystal form - rhombohedron is described to have?

A

6 identical faces with none of the intersection edges perpendicular

26
Q

What is a form in crystallography?

A

A group of crystal faces with the same relationship to symmetry

27
Q

Differentiate pedion and pinacoid.

A

Pedion (Monohedron) - singe face
Pinacoid (Parallelohedron) - 2 parallel faces

28
Q

Differentiate the 3 basic types of magnetism.

A

Ferromagnetism - strong magnetism
Paramagnetism - weak attraction, but most are strongly magnetic when heated
Diamagnetism - repelled from magnetic fields

28
Q

Globular is simply defined as:

A

radiating individuals forming spherical or hemispherical groups

29
Q

What is a mineraloid?

A

A mineraloid is a mineral -like substance that does not demonstrate crystallinity. (e.g. glass, opal, obsidian)

30
Q

What is a 2-fold rotation axis?

A

If an object appears identical after a rotation of 180 deg, that is twice in a 360 deg rotation, then it is said to have a 2-fold rotation axis.

31
Q

Expound open crystal form and give an example.

A

Open forms do not enclose space. Examples: Pedion, prism, pinacoid, domes, pyramid

32
Q

What are the geochemical affinities in the Goldschmidt Classification?

A

Lithophile - silicate (aluminum, boron)
Siderophile - iron (iridium, gold)
Chalcophile - sulfur (Copper, Sulfur)
Atmophile - gas (Helium, hydrogen)

33
Q

Which of the following are different from the other and why?

A. Sphenoids
B. Disphenoids
C. Pinacoids
D. Prism

A

A. Sphenoids - open form (mura atop)
B. Disphenoids - closed form (mura pyramid; 4 faces)
C. Pinacoids - open form (2 parallel faces)
D. Prisms - open form (3 or more parallel faces)

34
Q

Why is pedion an open crystal form?

A

Pedions are single faced forms. Since there is only one face in the form a pedion cannot completely enclose space. Thus, a crystal that has only pedions, must have at least 3 different pedions to completely enclose space.

35
Q

Expound the characteristics of the isometric crystal system (emphasizing symmetry elements) and provide examples.

A

Expound the characteristics of the isometric crystal system (emphasizing symmetry elements) and provide examples.

36
Q

Explain the concept of a crystal system and provide an example of a mineral for each of the six crystal systems.

A

The crystal system defines the geometric arrangement of crystal classes.

Examples:

Isometric (Cubic) - Pyrite
Hexagonal - Quartz
Tetragonal - Rutile
Orthorhombic - Topaz
Monoclinic - Azurite
Triclinic - Anorthite

37
Q

Explain the features of a prism crystal form. and a pyramid crystal form.
Provide examples of minerals with prismatic and pyramidal crystal habits.

A

Prism has parallel faces; pyramid has faces intersecting at a point. Examples: Monoclinic Prism - Augite; Tetragonal Pyramid - Rutile.

38
Q

What is the main reason why quartz have so many varieties?

A

Due to the different formation environments. Because of the different temperatures and pressure during the formation, different impurities can get into the quartz structure.

39
Q

Although objects themselves may appear to have 5-fold, 7-fold, 8-fold, or higher-fold rotation axes, these are not possible in crystals. Explain why.

A

The reason is that the external shape of a crystal is based on a geometric arrangement of atoms.

Note that if we try to combine objects with 5-fold and 8-fold apparent symmetry, they do not completely fill space as illustrated.

40
Q

Illustrate the silicate structure of (Mg,Fe)2SiO4.

A
41
Q

Illustrate the cleavage exhibited by pyroxenes.

A

two distinctive planes of cleavage with intersecting angles of about 87° and 93°

42
Q

Which of the following is different and why?

A. Deltoid dodecahedron
B. Tetrahexahedron
C. Hexagonal scalenohedron
D. Hextetrahedron

A

A. Deltoid dodecahedron - Isometric
B. Tetrahexahedron - Isometric
C. Hexagonal scalenohedron - Non-isometric
D. Hextetrahedron - Isometric

43
Q

Which of the following is true about a mineral? Provide a short explanation of each item.

A. It can be produced in a laboratory.
B. A solid substance that can be physically subdivided into simpler chemical compounds.
C. The atoms or groups of atoms must occur in specific ratios.
D. Includes compounds that contain carbon.

A

A. It can be produced in a laboratory. - must be naturally occuring
B. A solid substance that can be physically subdivided into simpler chemical compounds. - homogeneous means cannot be physically subdivided
C. The atoms or groups of atoms must occur in specific ratios. - means it has definite chemical composition
D. Includes compounds that contain carbon - inorganic means no carbon

44
Q

Give one variety of garnet and provide its composition and occurence.

A
45
Q

Give one variety of macroscopic quartz and provide its color and cause of color.

A
46
Q

Provide a mineral that have a greasy feel? Discuss how this occurred.

A

Minerals such as talc, graphite, and molybdenite possess a greasy feel. This results from weak van der waals bonds that allow the minerals to be broken into soft, dust-like fragments that “lubricate” the surface when the specimen is rubbed with the fingers.

DAY 2 - PETROLOGY AND MINERALOGY (1 decks)

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