key_terms_ass_5

Question 1

Aggregate

Answer 1

A solid mass of individual randomly oriented crystals intergrown or held together by a natural binding agent.

Question 2

Atom

Answer 2

The basic structural unit of all matter.

Question 3

Cleavage

Answer 3

A smooth flat break in a crystal parallel to a cleavage plane.

Question 4

Cleavage Plane

Answer 4

A planar surface along which a mineral tends to break due to atomic weakness.

Question 5

Covalent Bond

Answer 5

A chemical bond formed by two atoms sharing electrons.

Question 6

Crystal

Answer 6

Solid matter with atoms arranged in a regular repeating pattern.

Question 7

Crystal Axes

Answer 7

A reference system used to describe the symmetry and shape of crystals.

Question 8

Crystal Planes

Answer 8

Any set of parallel and evenly spaced planes distributed along certain crystal directions in which atoms are more closely packed.

Question 9

Crystal Shape (form)

Answer 9

The geometric shape of a well-formed crystal.

Question 10

Crystal Structure (lattice)

Answer 10

The regular repeating arrangement of atoms in a mineral.

Question 11

Crystal Systems

Answer 11

Categories of crystals based on their symmetry and internal structure.

Question 12

Crystalline

Answer 12

Composed of crystals or related to crystals.

Question 13

Defect

Answer 13

An imperfection or deviation from the ideal crystal lattice.

Question 14

Doubly Refractive (anisotropic)

Answer 14

Possessing different physical or optical properties in different crystal directions.

Question 15

Glassie

Answer 15

A well-shaped transparent octahedral diamond crystal with sharp square edges.

Question 16

Glide Plane

Answer 16

The plane or surface in which a dislocation travels through the crystal to cause an offset.

Question 17

Graining (Grain Lines)

Answer 17

Visible shadow-like lines in a diamond caused by glide planes in the crystal structure.

Question 18

Growth Marks

Answer 18

Visible features on the surface of a mineral crystal that reflect its internal growth and development.

Question 19

Habit

Answer 19

The characteristic crystal shape or form of a mineral.

Question 20

Line Defect (Dislocation)

Answer 20

Imperfection or deviation from the ideal arrangement of atoms in relation to a line in the crystal lattice.

Question 21

Macle

Answer 21

A flat triangular twinned diamond crystal.

Question 22

Octahedron

Answer 22

A crystal shape with eight equal triangular faces.

Question 23

Point Defect

Answer 23

An imperfection or deviation from the ideal arrangement of atoms in relation to a single atom or point in the crystal lattice.

Question 24

Resorption

Answer 24

The process in which the outer surface of a diamond is partially dissolved during transport.

Question 25

Singly Refractive (Isotropic)

Answer 25

Possessing the same physical or optical properties in all crystal directions.

Question 26

Specific Gravity (SG)

Answer 26

The ratio of the weight of a material to the weight of an equal volume of water.

Question 27

Spectroscopy

Answer 27

The study of the interaction between matter and light.

Question 28

Strain

Answer 28

Distortion or deformation in a crystal.

Question 29

Stress

Answer 29

The force required to produce distortion in the crystal lattice.

Question 30

Surface Graining

Answer 30

Colorless lines or grooves on a diamond crystal’s surface.

Question 31

Tetrahedron

Answer 31

In diamond a group of five carbon atoms with one at the center.

Question 32

Trace Elements

Answer 32

Atoms in a gem that aren’t part of its essential chemical composition.

Question 33

Trigon

Answer 33

A triangular depression or protrusion that occurs on a diamond’s octahedral faces.

Question 34

Twinned Crystal

Answer 34

Crystal consisting of two or more parts formed in a symmetrical manner with shared crystal planes.

Question 35

Unit Cell

Answer 35

The smallest group of atoms with the characteristic chemical composition and the basic crystal structure of a mineral.

Question 36

Vacancy

Answer 36

A point defect created when an atom is missing from its original position in the crystal lattice.

Question 37

Volume Defect

Answer 37

Imperfection or deviation from the ideal arrangement of atoms caused by a three-dimensional aggregate of atoms or vacancies within the crystal lattice.