Crystal Growth Flashcards

1
Q

Nucleation

A

First stage of growth, can only commence after a nucleus/seed has formed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Supersaturation

A

Usually required in solution for nucleation. Achieve by changing a mechanism (concentration, T and/or P).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Competing Tendencies for Nucleation and Growth in Cooling Magma

A

Thermal vibrations and attractive forces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Crystal Habit

A

External appearance of crystal and it’s combination of crystal forms. example: equant, fibrous, scaly, tabular.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

1) Euhedral
2) Anhedral
3) Subhedral

A

1) crystals display perfect polyhedral surfaces with regular interfacial angles.
2) Crystals with irregular surfaces.
3) Mixture of above two.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Twinning

A

Symmetrical intergrowth of two or more crystals of the same substance. Considered a type of planar defect.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Composition Surface

A

Surface that twinning are united.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Twin Plane

A

Reflection by a mirror plane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Twin Axis

A

Angular 180 degree rotation axis common to twinning crystals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Twin Center

A

Inversion about a point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Contact Twin

A

Have regular composition separating two individuals. Twins produced by either reflection or rotation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Penetration Twin

A

Made up of interpenetrating individuals having an irregular composition surface. Usually defined by a twin axis direction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Polysynthetic Twin

A

Multiple twins that have three or more crystals twinned AND all composition surfaces are parallel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Cause of Twinning -Growth Twins

A

Error in stacking of unit cells when crystal first starts to grow leads to twinning.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Causes of Twinning -Transformation Twin

A

Variations in T and P stresses lattice, warping to relieve stress leads to twinning.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Causes of Twinning -Deformation Twin

A

Stress put on crystal structure causes crystal to relieve pressure by twinning.

17
Q

Crystal Defects

A

As crystal grows, structural defects are incorporated into mineral. Affect growth rate, morphology, strength, conductivity and color.

18
Q

Point Crystal Defect

A

Represent holes in atomic structure.

19
Q

Edge Dislocation

A

Plane of atoms/ions terminate in a line instead of continuing.

20
Q

Screw Dislocation

A

Structural defect arranged along a screw axis.

21
Q

Radiation Defects

A

Minerals containing radioactive elements (U, Th) undergo decay. Alpha/beta particles and gamma radiation released from minerals.

22
Q

Polymorphism

A

Ability of chemical compound to crystallize with more than one structure. types: Reconstructive, displacive, order-disorder.

23
Q

Reconstructive Polymorphism

A

Major reorganization of the crystal structure. Atoms/ions rearranged and bonded into new structure/

24
Q

Displacive Polymorphism

A

Do not involve breaking atomic bonds, just slight displacement of atoms/ions and readjustment of bond angles.

25
Q

Order-Disorder Polymorphism

A

Different atomic species can occupy the same lattice site. No definite transition point between perfect order and complete disorder.

26
Q

Pseudomorphism

A

Replacement in which a mineral retains outward crystal form of another mineral species. Types: substitution, encrustation, alteration.