# Shared Flashcard Set

Mineralogy
final exam
156
Geology
12/19/2016

## Additional Geology Flashcards

Term
 Nicolaus Steno   niels bohr
Definition
 1669- Steno's Law of the constancy of interfacial angles   made fundational contributions to understanding atomic structure and quantum theory
Term
 Rene Just Hauy   auguste bravais
Definition
 1743-1882: the father of modern crystallography coined the word molecule unit cell 2D vs 3D   His crystal lattice concept is used to formally define a crystalline arrangment
Term
 william hallowes miller   symmetry
Definition
 came up with crystal faces notation in crystallography   the consistency, the repetiton of something in space and/or in time
Term
 2-D
Definition
 17 possible ways of repeating a motif
Term
 3-D
Definition
 230 possible ways of repeating a motif
Term
 operations
Definition
 ways of repeating space; any motion that brings the original motif into the same motif elsewhere in the pattern
Term
 translation (t)
Definition
 generates a pattern at regular identical intervals
Term
 reflection (m)
Definition
 a mirror plane: when looking in a mirror, the resultant image is identical except every part has been translated an equal and opposite direction across and perpendicular to the plane of the mirror
Term
 rotation
Definition
 pattern generated by rotating a motif around an imaginary axis
Term
 inversion (i)
Definition
 motifs are an equal and opposite distance through a point rather than through a plane
Term
 glide (g)
Definition
 two steps: motif is reflected across a mirror plane, then translates (moves)
Term
 Fold rotations
Definition
 1-fold= 360 2 fold=180 3 fold= 120 4 fold= 90 6 fold= 60
Term
 rotoinversion
Definition
 rotation plus inversion
Term
 point groups
Definition
 combining more than one axis of rotation generates regular three dimensional patterns
Term
 6 unique 2-D symmetry operations
Definition
 1 2 3 4 6 m
Term
 6 original elements plus the 4 combinations 2-D point groups
Definition
 1 2 3 4 6 m 2mm 3m 4mm 6mm   any 2-D pattern of objects surrounding a point must conform to one of these groups
Term
 10 unique 3-D symmetry
Definition
 1 2 3 4 6 i m -3 -4 -6   a complete analysis of symmetry about a point in space requires that we try all possible combinations of these symmetry elements
Term
 22 possible unique 3-D
Definition
 there are only 22 possible unique 3-D combinations, when combined with the 10 original 3-D elements yields the: 32 3-D point groups
Term
 lattice
Definition
 imaginary pattern of points. every point has same environment
Term
 motif
Definition
 repetition of the unit cell creates a motif smallest unit of a structure that can be indefinitely repeated to generate the whole structure.
Term
 unit cells
Definition
 arranged in a pattern described by points in a lattice   we often envision translational symmetry by thinking about a lattice
Term
 cubic
Definition
 a=b=c  alpha=beta=gamma=90 degrees
Term
 tetragonal
Definition
 a=b does not = c alpha=beta=gamma=90 degrees
Term
 orthorhombic
Definition
 a does not = b does not = c alpha=beta=gamma=90 degrees
Term
 hexagonal
Definition
 a=b does not =c alpha=beta=90 degrees gamma= 120 degrees
Term
 monoclinic
Definition
 a does not = b does not = c alpha=gamma=90 degrees beta does not = 120 degrees
Term
 triclinic
Definition
 a does not = b does not = c alpha does not = beta does not = gamma does not = 90
Term
 convention
Definition
 all crystals except hexagonal referred to by 3 axes: a,b, and c alpha is angle between b and c beta is angle between a and c gamma is angle between a and b
Term
 basic isometric crystal shapes
Definition
 octahedron, cube, cube with striations, trapezohedron, dodechedron
Term
 miller indices
Definition
 represent intercepts of crystal faces upon crystal axes 1a,1b,1c 1/1,1/1,1/1 invert it, 1/1,1/1,1/1   (1,1,1)
Term
 crystal form
Definition
 general form (h,k,l) 48 forms (32 general, 16 special: 10 closed isometric; 6 open prisms)
Term
 point groups
Definition
 are a group of operations that repeat a motif around a single point
Term
 plotting crystal faces on a stereo diagram
Definition
 -normals drawn to crystal faces to project them on to a sphere -the points in the sphere are projected onto an equatorial plane -where they hit the equatorial sphere is a stereo diagram
Term
 crystal
Definition
 a substance with a systematic internal arrangement of atoms or molecules
Term
 atom
Definition
 smallest particles of an element that retain the element's chemical properties
Term
 element
Definition
 form of matter that cannot be decomposed by heat, cold, or reaction
Term
 atoms are composed of three fundamentally different particles
Definition
 1) neutrons are electrically neutral particles in the nucleus 2) protons are positively-charged particles in the nucleus 3) electrons are negatively-charged particles that surround the nucleus
Term
 atomic number
Definition
 atomic number=number of protons
Term
 atomic mass
Definition
 number of protons+number of neutrons
Term
 isotope
Definition
 atoms with the same number of protons, but different numbers of neutrons
Term
 cations
Definition
 if they lose electrons (lose negative charge)
Term
 anions
Definition
 if they gain electrons (gain a negative charge)
Term
 electronegativity
Definition
 propensity of an element to gain or lose electrongs
Term
 oxidation
Definition
 lose an electron
Term
 reduction
Definition
 gain electron, expand shell
Term
 monovalent
Definition
 ions with a charge of +1 and -1
Term
 divalent
Definition
 ions with a charge of +2  or -2
Term
 trivalent
Definition
 ions with a charge of +3 or -3
Term
 cation size and the periodic table
Definition
 cations are usually smaller than anions ions increase in size down the PT ions decrease in size across the PT
Term
 bonding in minerals
Definition
 ionic, covalent, metallic, hydrogen bonds, van der waals
Term
 ionic
Definition
 oppositely charged ions attract cations, anions loss or gain of an electron, no sharing Na+ + Cl- = NaCl in halite
Term
 covalent
Definition
 sharing electrons very strong bonds form when adjacent atoms have similar or equal electronegativites diamond, H2
Term
 metallic
Definition
 electrostatic forces among electron clouds less common in rock forming minerals, but very important for minerals like copper, gold strong metallic bonding indicated by high melting points of metals   sharing of many detached electrongs between positive ions (electron cloud)
Term
 intermolecular
Definition
 hydrogen bonding weak
Term
 ionization potential
Definition
 the amount of energy required to pull off the first, second... electron from an atom
Term
 electronegativity
Definition
 the ability of an atom in a crystal structure or molecule to attract electrongs to its outer shell low=electron  donors high= electron acceptors
Term
 van der waals
Definition
 weak bonds: relatively weak electrostatic forces from uneven charge distribution in crystal structure. weakest attractions found in minerals   ties unchargee or neutral molecules together into a cohesive unit using small residual charges on their surface
Term
 hydrogen bonds
Definition
 relatively weak (but stronger than van der waals)
Term
 Why petrographic microscopes?
Definition
 -ID minerals with confidence (rock type, rock composition, P-T-X conditions of formation) -observe rock microstructures (crystallization sequence, paragenesis and reactions, deformation) -fun, powerful, and cheap
Term
 What do petrographic microscopes do?
Definition
 Creates a series of controlled interactions between visible light and minerals, which (hopefully) yield diagnostic responses
Term
 optical microscopy
Definition
 the study of minerals in thin section using visible light
Term
 wave theory
Definition
 light phenomena involve both particle and wave behavior. everything we encounter with crystals and the microscope is explained by wave theory.
Term
 electromagnetic waves
Definition
 interaction between the light waves moving through a crystal and the atoms in a crystal is what controls the speed of light in the crystal
Term
 λ
Definition
 wavelength
Term
 a
Definition
 amplitude of the wave
Term
 V
Definition
 velocity of light in a crystal
Term
 f
Definition
 frequency f=velocity/wavelength   number of wave crests per second passing a particular point -usually expressed as cycles per second (hertz Hz)
Term
 light consists of...
Definition
 many waves, not one!
Term
 wave front
Definition
 surfaces connectin equivalent points on adjacent waves
Term
 wave normal
Definition
 a line drawn perpendicular to the wave front =direction wave front is moving
Term
 light ray
Definition
 direction of propagation of light energy
Term
 polarization
Definition
 light that vibrates in one direction   -unpolarized light vibrates in all directions -plane polarized light vibrates in 1 direction
Term
 reflection
Definition
 reflected light vibrates parallel to the reflecting surface, rest is absorbed (polarized sunglasses that reduce glare)
Term
 absorption
Definition
 absorbed by an anisotropic mineral; two polarized rays created- one absorbed one emerges
Term
 double refraction
Definition
 absorbed by an anisotropic mineral; two polarized rays emerge, and we use one
Term
 when light pases through a material...
Definition
 velocity changes light is refracted (rays bent) light is split into 2 new vibration directions usually see new colors
Term
 when light enters a crystal...
Definition
 it is split into two different waves known as double refraction. There are two basic classes of how these two light waves are affected by mineral structure: isotropic anisotropic
Term
 isotropic
Definition
 transmit light in all directions at equal velocity i.e. do not reorient light
Term
 anisotropic
Definition
 reorients light and splits it into 2 perpendicular plane-polarized components that travel at different velocities.
Term
 f is constant
Definition
 light slows when it enters a medium (waves bunch up) =change in velocity and wavelength of light when it moves   denser medium=more electrons=more interactions with light=more energy transferred from the light to the electrons in the medium (light is slowed down more)
Term
 Refractive Index (RI or n)
Definition
 Non-perpendicularly-incident light is refracted when it passes from one substance to another; refraction is accompanied by a change in velocity   n=velocity of light in vacuum/velocity of light in mineral
Term
 isotropic minerals (RI)
Definition
 characterized by one RI
Term
 anisotropic minerals (RI)
Definition
 characterized by two or three RI
Term
 n gives rise to...
Definition
 relief and birefringence
Term
 snell's law and the O-ray
Definition
 light striking the surface of the material at right angles should go straight through without deviating
Term
 extraordinary ray
Definition
 waves don't obey snell's law
Term
 optical indicatrix
Definition
 imaginary 3D surface inside a crystal where axial lengths are proportioal to the refractive index in that direction
Term
 three types of optical indicatrices
Definition
 isotropic, anisotropic (uniaxial, biaxial)
Term
 Relief
Definition
 observed in Plane polarized light   relief is a measure of the relative difference in n between a mineral grain and its surroundings
Term
 becke line
Definition
 observe the direction that becke line (the white line) moves as the distance between the stage and the ocular increases (as the stage drops)   positive relief-becke lines move in negative relief- becke lines move out
Term
 color
Definition
 observed in PPL results from selective absorption of certain wavelengths of light
Term
 pleochroism
Definition
 observed in PPL results when different wavelengths are absorbed diffently by different crystallographic directions (as the stage rotates)
Term
 interference colors
Definition
 light splits into two rays: observed in XPL produced because most solids have more than one index of refraction=rays have different velocity   slow and fast rays emerge from the grain, combine to produce interference colors
Term
 plane polarizd light-isotropic minerals
Definition
 crystal habit (sections through crystals) cleavage relief color in plane polarized light inclusions; color banding; intergrowths; alteration; oxidation
Term
 extinction
Definition
 anisotropic minerals turn dark once every 90 degrees why? one vibration direction is parallel to the lower polarizer. no light passes through vs max interference colors
Term
 extinction categories
Definition
 parallel inclined symmetrical no extinction angle
Term
 accessory plates
Definition
 mica plate- retardation of 147 nm quartz wedge used to determine slow vs fast rays vibration directions in elongate minerals
Term
 sign of elongation
Definition
 1) extinction position 2) turn 45 degrees 3) insert 1 wavelength plate 4) observe changes in interference colors 5) determine if slow on slow or slow on fast
Term
 Anisotropic minerals in PPL
Definition
 shape (crystal form) cleavage relief point count inclusions alteration
Term
 Pleochrosim- yellow
Definition
 parallel to the lower polarizer (fast)
Term
 Pleochroism-green
Definition
 parallel to te lower polarizer (slow)
Term
 crystal systems classified: isotropic
Definition
 isometric -all crystallographic axes are equal -chemical bondin the same in all directions
Term
 crystal systems classified: uniaxial
Definition
 hexagonal/trigonal, tetragonal -all axes except c are equal but c is unique (a high degree of symmetry about the c axis)
Term
 crystal systems classified:biaxial
Definition
 orthorhombic, monoclinic, triclinic -all axes are unequal, therefore vary in every direction in crystal structure and chemical bonding
Term
 isotropic-interference figure
Definition
 light travels the same distance/velocity in all directions so n is same everywhere thus no interference figure is produced.
Term
 anisotropic: uniaxial minerals
Definition
 one circular axis of revolution= optic axis optic axis always along the c-axis in these systems   all other directions: light rays find the fastest and slowest vibration direction and break into two rays of different velocities.
Term
 interference figures for uniaxial minerals
Definition
 produced when we examine light that travels in many directions through a crystal at once
Term
 melatope
Definition
 center of optic axis figure
Term
 isogyres
Definition
 lines of optic axis figure
Term
 colored lines
Definition
 isochromes of optic axis figure
Term
 quartz
Definition
 uniaxial postive
Term
 NOME
Definition
 uniaxial negative: NOME: omega more than epsilon
Term
 calcite
Definition
 uniaxial negative
Term
 molten materials divided into several different sorts of melts
Definition
 -one rich in Fe alloys -another rich in sulfide compounds -one containing silicates
Term
 classification
Definition
 chemical elemens distribute themselves between those three groups (one rich in Fe alloys, another rich in sulfide compounds, one containing silicates)
Term
 siderophile
Definition
 elements that concentrate in Fe-rich liquid (iron loving)
Term
 chalcophile
Definition
 elements that concentrate in S-rich liquid
Term
 lithophile
Definition
 elements that concentrate in silica-rich liquid (rock loving)
Term
 atmophile
Definition
 elements that form a gas   escaped the interior of the earth and made our atmosphere
Term
 Earth's main elements
Definition
 oxygen, silicon, aluminum, iron, magnesium
Term
 crystal
Definition
 a solid compound having an ordered, repetitive, atomic structure
Term
 how do minerals form?
Definition
 Solidification, precipitation, recrystallization
Term
 solidification
Definition
 from molten rock (magma) in igneous rocks
Term
 precipitation
Definition
 from an aqueous solution at o near the Earth's surface (sedimentary rocks)
Term
 recrystallization
Definition
 in the solid state, in response to changes in heat and pressure (metamorphic rocks)
Term
 morphology
Definition
 study of external crystal form
Term
 euhedral
Definition
 faces of a mineral are fully developed
Term
 subhedral
Definition
 shapes are between euhedral and anhedral
Term
 anhedral
Definition
 no visible crystal faces
Term
 differential rate of cooling
Definition
 affects the type of crystals that grow -the faster a magma cools, the less distinct and smaller the crystal shapes become.   temperature. at high temperatures, atoms are very mobile and crystals can grow more quickly   flux: availability of the major elements needed to grow a particular mineral
Term
 factors that affect crystal growth morphology
Definition
 space to grow   defects in the crystal lattice -line and point dislocations -planar defects (twinning in the crystal lattice) -compositional zoning
Term
 space to grow
Definition
 geodes have euhedral crystals because they grow out into open (solution-filled) space.   the growth of individual grains is not impeded by the surrounding grains
Term
 crystal defects can affect...
Definition
 strength, conductivity, rock deformation style, color
Term
 point defects
Definition
 vacancies frenkel defect impurity atom (interstitial)
Term
 line defects
Definition
 edge dislocation screw dislocation
Term
 planar defects
Definition
 twinning extremely common and important
Term
 Point defects- schottyky defect-vacancy of ion
Definition
 can help maintain charge balance foreign ion replaces normal one -solid solution -not considered a defect
Term
 point defects impurity ion
Definition
 foreign ion is added called an iterstitial ion
Term
 point defects- frenkel defect
Definition
 ion hops from lattic site to intersititial
Term
 line defects- screw dislocation
Definition
 planes displaced relative to each other through shear (spiral sliced ham)   aids mineral growth
Term
 line defects- edge dislocation
Definition
 migration of ions aids ductile deformation of rocks
Term
 planar defects...
Definition
 mismatch of the crystal structure across a surface offically grain boundaries count as planar defect   twining rational symmetrcally-related intergrowth lattices of each orientation have ddefinite cystallographic relation to each other
Term
 ideal crystals twinning
Definition
 atoms in repetiive arrangements, same orientatio in all parts of crystal
Term
 twins
Definition
 domains of a crystal grow in different atomic orientations. share atoms along a common surface (the composition plane) (still considered the same mineral grain)
Term
 contact twins
Definition
 simple twins twins appear to be crystals in contact
Term
 penetration twins
Definition
 simple twins a volume of atoms (not just a plane) is shared between the two domains
Term
 more complex twinning
Definition
 multiple twins-several twin segments repeated by same twin law cyclic twins- multiple twins not parallel polysynthetic twins- multiple twins parallel
Term
 si and O
Definition
 most abundant elements in crust and mantle   -therefore most imporant bond in mineralogy
Term
Definition
 -change in T with depth in earth -steeper with depth -does not intersect the melting curve for peridotite -melting is not common in earth's subsurface
Term
 transfer of heat
Definition
 repeated intrusions can transfer enough heat to increase the local geothermal gradient and cause melting of the surrounding rock to generate new magmas.
Term
 liquidus versus solidus
Definition
 molten rock crystallizes over a range of T partial melt=less dense than surrounding rock rises and cools and begins to crystallize 1st crystals form at the liquidus the last drop of melt crystallizes at the solidus
Term
 igneous rock textures
Definition
 very fast cooling: glassy rock=obsidian fast cooling: aphanitic (small crystals-fine grained) slow cooling: phaneritic (big crystals coarse grained)
Term
 formation of igneous rocks
Definition
 when magma or lava cools, different minerals form in sequence until the melt solidifies (freezes) and igneous rock forms
Term
 fractional crystallization
Definition
 the mafic minerals that melt at highest temperatue begin to crystallize first when the magma cools. these higher density minerals sink to the bottom of the chamber. elements incorporated into these minerals are extracted from the melt, leaving the melt with a more silicic composition
Term
 volatiles
Definition
 melt inclusions are small droplets of magma trapped in crystallizing minerals such as olivine.
Term
 exsolution
Definition
 initially homogeneous solid solution separates into at least 2 different crystalline minerals -no addition or removal of any materials -in most cases, it occurs upon cooling below the temperature of mutual solubility or stability of the solution.
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