Lesson 2: Physical Properties of Mineral

Question 1

Crystal Form and Crystal Habit

Answer 1

• Morphology
• Form
• Habit
• Unit Cell
• Aggregate

Question 2

• completely bounded by crystal
• growth during primary crystallization or recrystallization was not restrained or interfered with by adjacent grains, and the faces were not greatly affected by late physical or chemical erosion

Answer 2

Euhedral Crystals (idiomorphic or automorphic)

Question 3

• partly bounded by crystal and partly by surfaces formed against pre-existing grains
• minerals were able to crystallize with their characteristic habit only in part, due to the presence of neighboring crystals that partly constrained their growth

Answer 3

Subhedral (ipidiomorphic)

Question 4

• lacks crystal faces and shows rounded or irregular surfaces due to crowding of adjacent minerals
• e.g. embayed crystals with irregular outline, but also interstitial grains that grew in the space left between other, pre-existing crystals

Answer 4

Anhedral (xenomorphic or allotriomorphic)

Question 5

The outward expression of the internal ordered atomic arrangement of a crystal

Answer 5

Morphology

Question 6

Consists of a group of crystal faces which have the same relation to the elements of symmetry

Answer 6

Form

Question 7

Includes the general shape of a crystal and its
growth irregularities

Answer 7

Habit

Question 8

The smallest unit of structure that if stacked indefinitely in three dimensions would form the whole structure (further discussion in Crystallography)

Answer 8

Unit cell

Question 9

Minerals whose crystals come in groups (e.g. thousands of crystals intimately intergrowing to form unique aggregate shapes)

Answer 9

Aggregate

Question 10

For a crystal with one dimension markedly longer than the other two

Answer 10

Prismatic

Question 11

With the external form of a rhombohedron

Answer 11

Rhombohedral

Question 12

With the external form of a cube

Answer 12

Cubic

Question 13

With the external form of an octahedron

Answer 13

Octahedral

Question 14

With the pronounced development of one or more two-sided forms (pinacoid)

Answer 14

Pinacoidal

Question 15

Crystals are roughly equidimensional

Answer 15

Equant

Question 16

Flat and plate-like but crystals are typically thin and can be stacked on top of each other like sheets of paper

Answer 16

Lamellar

Question 17

Flat and plate-like but have lengths and widths that are much larger than their thickness

Answer 17

Tabular

Question 18

Crystals are elongated and flattened, like a knife blade, crystals are much longer than they are wide, and their width exceeds their depth

Answer 18

Bladed

Question 19

Form as thin, flat sheets or flakes that are easily peeled or split off the larger mass

Answer 19

Micaceous

Question 20

when edges are fully developed but the interior spaces are not filled in (hollowed-out step lattice formation)

Answer 20

Hopper

Question 21

Crystal growth that produces fine, feathery scales from the Latin “pluma” = feather (fan-like or feather-like)

Answer 21

Plumose

Question 22

needlelike, contains long, slender crystals which may radiate out like needles or bristles from a common base

Answer 22

Acicular

Question 23

exhibits hairlike or threadlike filaments (Latin
“filum” = thread)

Answer 23

Filiform

Question 24

exhibits clumps of sinewy, stringy, or hairlike fibers, the direction of growth is parallel to the longest dimension of the crystal

Answer 24

Fibrous

Question 25

Crystals are interconnected in a network or lattice-like pattern (Latin “rete” = net)

Answer 25

Reticulated

Question 26

Possesses several branches that radiate outwards from the center in a pattern resembling a star

Answer 26

Stellated

Question 27

crystals have a branching, tree-like appearance, dendrites are formed when the crystals grow in a supercooled liquid (when liquid is below its freezing point but not yet frozen)

Answer 27

Dendritic

Question 28

crystals are spherical, rounded, or bulbous (Latin “collo” = glue)

Answer 28

Colloform

Question 29

resembling a bunch of grapes (Greek “botrus” =bunchof grapes

Answer 29

Botryoidal

Question 30

crystals are rounded and have a bumpy or knobby surface (Latin “mammilla” = nipple

Answer 30

Mammillary

Question 31

displays the kidney shape (Latin “renes” kidney)

Answer 31

Reniform

Question 32

spherical or oval-shaped and typically less than 4mm in diameter found in sed rocks (limestone & dolomite)

Answer 32

Oolitic

Question 33

Develops round, pea-shaped forms and are larger and slightly more uneven than oolite (Greek “pisos” = pea)

Answer 33

Pisolitic

Question 34

Tall, tapered, collum-like appearance of an icicle from the dripping of mineral-laden solution (Greek “stalaktos” = dripping)

Answer 34

Stalactitic

Question 35

crystals are formed by the concentric deposition of mineral matter around a nucleus (rock, plant or animal remain, gas bubble, etc)

Answer 35

Concretionary

Question 36

Crystals have parallel lines or grooves on their surface

Answer 36

Striated

Question 37

Crystals are tightly packed together and form a kind of crust or coating on a surface

Answer 37

Drusy

Question 38

Crystals grow in a direction that minimizes the surface energy of the crystal

Answer 38

Columnar

Question 39

Large, lumpy mass with no apparent crystal form

Answer 39

Massive

Question 40

Commonly given to describe the orientation of the form with respect to crystallographic axes

Answer 40

Miller Index

Question 41

- Aggregates of similar crystals with their crystallographic axes and faces parallel - represents a single crystal despite having the appearance of several crystals since its internal (atomic) structure remains unchanged in orientation

Answer 41

Parallel growth

Question 42

- A symmetrical intergrowth of two (or more) crystals of the same substance - the two or more individuals of the twinned aggregate are related by a symmetry element that is absent in the original (untwinned) crystal

Answer 42

Twin

Question 43

➢ have a planar composition surface separating two individual crystals ➢ usually defined by a twin law that expresses a twin plane ➢ E.g. orthoclase twinned on the Braveno Law {021} as the twin plane

Answer 43

Contact Twin

Question 44

Penetration Twin

Answer 44

➢ Have irregular composition surface separating two individual crystals ➢ usually defined by a twin center or twin axis ➢ E.g. orthoclase twinned on the Carlsbad Law, [001] as the twin axis

Question 45

If the composition surfaces are parallel to one another

Answer 45

Polysynthetic Twins

Question 46

if the composition surfaces are not parallel to one another

Answer 46

Cyclical Twins

Question 47

Refers to the general appearance of a mineral surface in reflected light

Answer 47

Luster

Question 48

Like a metallic surface such as chrome steel, copper, and gold

Answer 48

Metallic

Question 49

shown by light-colored minerals that transmit light, not metallic

Answer 49

Non metallic

Question 50

The amount of light that a mineral can transmit

Answer 50

Diaphaneity

Question 51

Capable of transmitting light and through which an object may be seen

Answer 51

Transparent

Question 52

Capable of transmitting light diffusely

Answer 52

Translucent

Question 53

Mineral that is impervious to visible light

Answer 53

Opaque

Question 54

the striking flashes of varied color against a white or black background (e.g. opal)

Answer 54

Play of Color

Question 55

Caused by light diffracted and reflected from closely spaced fractures, cleavage planes, twin lamellae, exsolution lamellae, or minute foreign inclusions in parallel orientation.

Answer 55

Iridescence

Question 56

An optical phenomenon in which a band of reflected light, known as a “cat’s eye," moves just beneath the surface of a cabochon-cut gemstone

Answer 56

Chatoyancy

Question 57

- triple chatoyancy - the result of scattering of light from inclusions in directions

Answer 57

Asterism

Question 58

Any emission of light by a mineral that is no direct incandescence

Answer 58

Luminescence

Question 59

A mineral that luminesces during exposure to ultraviolet light, x-rays, or cathode rays

Answer 59

Fluorescence

Question 60

when a mineral exposed to ultraviolet light, x rays, or cathode rays continues to luminesce after the exciting rays are cut off

Answer 60

Phosphorescence

Question 61

➢ Minerals like Quartz, Feldspars, Halite (10^-5 Slu) ➢ E.g. massive salt deposits that contrast with the positive magnetic susceptibility of the adjacent sedimentary rocks containing detrital magnetic grains

Answer 61

Diamagnetism

Question 62

➢ Magnitude is inversely proportional to temperature (Curie’s law) ➢ Magnetic susceptibility ranges from 10^-3 to 10^-5 Slu ➢ Possessed by minerals like biotite, pyroxene, amphibole, olivine, and garnet

Answer 62

Paramagnetism

Question 63

➢ Magnetism of ferrous metals (iron) ➢ At the Curie Temperature, ferromagnetic materials take on the properties of a paramagnetic material without the intense magnetism and the magnetic field memory

Answer 63

Ferromagnetism

Question 64

➢ Most common form of magnetism causing magnetic anomalies ➢ Source of all magnetization in Earth materials ➢ Magnetite – principal naturally occurring ferrimagnetic component in the Earth

Answer 64

Ferrimagnetism

Question 65

Mineral that breaks and powders easily

Answer 65

Brittle

Question 66

A mineral that can be hammered out into thin sheet

Answer 66

Malleable

Question 67

Mineral that can be cut into thin shaving with a knife

Answer 67

Sectile

Question 68

Mineral that can be drawn into a wire

Answer 68

Ductile

Question 69

Mineral that bends but does not resume its original shape when the pressure is released

Answer 69

Flexible

Question 70

After the pressure is released, the mineral will resume its original position

Answer 70

Elastic