POLARIZING MICROSCOPE TECHNIQUES AND APPLICATIONS Flashcards
Used extensively to examine transparent minerals, fragments, grains and small crystals, as well as thin sections of minerals, rocks and other crystalline aggregates
Polarizing Microscope
useful in the determination of the optical properties of individual crystals or aggregates and in the interpretations of textures, structures, growth patterns, and various relationship of natural or artificial substance.
Polarizing Microscope
source of light of the microscope
Light source
Concentrates light
Collector lens system
controls light ray bundle at
the source field
Field iris diaphragm with
field iris diaphragm ring
Approximates daylight
note that they only use blue filter before bc the light is yellow
Filter mount with blue
filter
used to polarize the light in one direction
Polarizer
It controls and illuminates light coming from the source field directed to the object field.
Condenser
controls cone of light catering the objective
Aperture Iris Diaphragm
It is useful for R. I. determination
Aperture Iris Diaphragm
platform for specimen
Stage
Fix specimen on stage
Stage Clips
Used for point locations and systematic traverse in a species along mutually perpendicular directions
Mechanical Stage
Part of the microscope that we
move left to right.
based on discussion
Mechanical Stage
the amount of space between the front of the objective and the top of the coverglass, when the specimen is in focus
definition is from google but it was discussed
Free working distance
For Focusing Image (moving in cm)
Coarse Adjustment Knob
For Focusing Image (moving in mm)
Fine Adjustment Knob
holds objectives
Revolving Nosepiece
Essential lenses of microscope for magnification and resolution
Objectives initial
Magnifications of the Objectives initial
4x, 10x, 20x, 40x
for insertion of microscopic
accessory plate
Test plate
polarizes light
Analyzer
for observing interference
figure
Bertrand lens
Holds the eye piece
Observation tube
essential lenses of microscope for magnification or resolution conform with objectives
Eyepieces with cross hair
for focusing eyepieces
Diopter adjustment ring
for camera attachment in
photomicrography
Photo Tube
cut to such thickness that it increases or decreases retardation of a section by about 1/4λ (sodium light)
mica plate
used to **determine fast and slow directions (electric vectors) of light polarization **in crystals under view on the microscope stage by increasing or decreasing retardation of the light
Gypsum plate
ground to produce interference colors from the
beginning of the first to the end of the third or fourth order.
quartz wedge
quartz wedge equals to?
0.009
Beam of** light consists of a stream of minute particles, or photons,** given off at high velocity by a luminous body that travel through space in straight lines and eventually reach the eye.
Corpuscular Theory
The (Dutch) scientist that advanced the Wave Theory
Christian Huygens
light to be transmitted by the vibration of particle in the waves
Wave Theory
The phenomena of light such as reflection, refraction, diffraction and interference may be readily explained in accordance with this theory
Wave Theory
He proposed the Electromagnetic Theory in 1873
James Clerk Maxwell
considers light as made up of waves but said that waves are electromagnetic
Electromagnetic Theory
A wave consists of rapidly alternating electric and magnetic fields normal to each other and normal to the direction of propagation of light
Electromagnetic Theory
Assuming that radiating oscillators in a black body radiate energy discontinuously in units called quanta.
Quantum Theory
He proposed the Quantum Theory
Planck / Max Planck
The locus of all the points of a medium which receives light wave disturbance simultaneously so that all points are in the same phase.
Wave Front
A perpendicular drawn to the surface of a wave front at any direction of propagation of light
Wave Normal
Direction in which the light is propagated
Ray of Light
It is alway perpendicular to wave front
Ray of Light
Wave front always carries light energy in a direction ____________ to its surface
perpendicular
A wave normal represents a _________________
Ray of Light
The wave normal and direction of propagation of light rays are** perpendicular to the wave front.**
Isotropic
The light rays are** not parallel to the wave front.**
Anisotropic
May represent a curve combining movement around a circle with motion along a straight line.
Displacement
Lies in the wavefront and is perpendicular to the ray in isotropic media.
Vibration direction
In ____________, Vibration direction is only perpendicular in limited directions.
anisotropic media
Distance between two successive crests or troughs, or any corresponding distance along the wave.
Wavelength
Surface determined at a given instant by all parts of a system of waves traveling along the same direction and in the same phase.
Wavefront
wavefront is perpendicular only in certain directions in?
anisotropic
Direction perpendicular to the wave front
Wave Normal
In _________________ the wave normal and ray direction are the same
Isotropic
In ______________, they differ aside from certain directions
anisotropic
number of vibrations in a given unit of time.
Frequency
maximum displacement of a wave from the line of transmission
Amplitude
time interval necessary for a wave to undergo a complete oscillation
Period
point of the wave with the maximum upward displacement
Crest
point of the wave with the greatest downward displacement
Trough
a group of light waves following along a sample path
Beam
straight-line path followed by light in moving from one point to another
Ray
equal to the ratio of the wave-normal velocity in a vacuum to the wave-normal velocity in the medium whether isotropic or anisotropic
Refractive index
light of a single wavelength
Monochromatic light
lies parallel to the plane of the wavefront.
Light vector
In ____________ , Light Vector is perpendicular to the direction of the propagation
isotropic
In ______________ , Light vector is still
parallel but not perpendicular to the direction of the propagation.
anisotropic
2 Types of Vector
- electric
- magnetic
measures the electrical displacement
electric
measures the magnetic displacement or induction.
magnetic
Speed of light
186,284 miles per second
combination of all the different wavelengths visible to the eye
White light
realistic virtual image with a flat field
Orthoscopic observation
Setting of Orthoscopic Observation Plane Polarized Light (Uncrossed Nicols)
- Low to high magnification objective
- Analyzer Out
- Condenser top lens out
- Bertrand lens out
Setting of Orthoscopic Observation (Crossed Nicols)
- Low to High magnification objective
- Analyzer In
- Condenser top lens out
- Bertrand Lens out
yields interference figures which represent
an optical pattern caused by the behavior of light in individual crystal
Conoscopic observation
Setting of Conoscopic Observation
- High Magnification Objective (40x)
- Analyzer in
- Condenser top lens in
- Bertrand lens in
- Accessories in
In sample preparation when cutting using the cutting machine it should be at least ___________ size
1’‘x 2’’
In sample preparation when grinding the size should be
240 mesh abrasive to 800 mesh
In Heating in sample preparation both ________________________ put Canada Balsam in thin section and heat it for about 30 minutes
the thin section and the sample in a hot plate
In Heating in sample preparation both the thin section and the sample in a hot plate put ______________ in thin section and heat it for about 30 minutes
Canada Balsam
In Heating in sample preparation both the thin section and the sample in a hot plate put Canada Balsam in thin section and heat it for about ________________
30 minutes
In sample preparation when the sample is put in thin section it is called
Mounting
Can be used in Cutting in sample prep
Diamond saw cutter
Sample can also be grind in a ________________________
300 mesh abrasive up to at least 0.03 mm thickness
Cover the thin section with the sample using the ______________
Cover Slip
Clean the thin section using the ________________
xylol solution
Study of the interaction of light with minerals
Optical Mineralogy
Opaque minerals commonly studied in reflected light
ore microscopy
general application of optical mineralogy is?
to aid in the identification of minerals, either in rock thin sections or individual mineral grains
It has Low power objective (10x) and Bertrand lens is optional
Orthoscopic (Uncrossed)
Properties that can be observed in Orthoscopic
[] Color and Pleochroism
Cleavage
Shape and Form
Relief/ Refractive Index (R.I.
observed w/ plane prolonged light; not always the same as megacopic color
Color
change in color of a mineral in varying degrees as the stage is rotated due to differences in light absorption & extraordinary rays generally expressed as a formula
Pleochroism
The ability of a mineral to separate into smaller
particles bounded of faces of possible crystal form.
Cleavage
Cleavage is expressed or best explained in terms of __________
direction
qualities of cleavage
[] Perfect
Good
Poor
None
Directions of Cleavage
One Direction
Two Directions
Three Directions
Four Directions
Six Directions
All Directions
can be expressed by using the terms
euhedral subhedral anhedra
Shape and Form
Grains that show no recognizable crystal form
anhedral
Grains that show imperfect but recognizable
crystal form
subhedral
Grains that show sharp and clear crystal form
euhedral
degree of visibility of a transparent mineral in an immersion medium
Relief
A function of the difference n mineral and n medium
Relief
R.I of Canada balsam
1.53
index of refraction (R.I) of the mineral is Higher than the medium
High Relief
R.I of the mineral is lower than the medium
Low Relief
almost the same with the medium
Zero Relief
varies as the stage is rotated, takes place if one n mineral is near n balsam, and the other n mineral
Change of Relief
the contrast between a mineral and its
surroundings due to difference in refractive index.
Relief
Relief is __________ when the grain has higher refractive index than surroundings
positive
Relief is __________ when the grain has lower refractive index than surroundings
negative
Strong negative relief is limited mostly to _____________ like fluorite
non-silicates
ratio of the velocity of light in a vacuum to its
velocity in the medium
Refractive Index
R.I. constant velocity in all directions
isotropic/ isotropic substances
more than one R.I, light velocities vary with direction
anisotropic
a band or rim of light visible along a grain/crystal boundary in plane-polarized light.
Becke line
It is best seen using the intermediate power lens (or low power in some cases), on the edge of the grain, with the diaphragm stopped down a bit
Becke line
If the refractive index is higher than the mounting medium the rays converge towards the ___________ of the grain
Center
If the refractive index is lower, the rays diverge towards the ______________ of the grain
Edge
In using Becke line to determine the relief: make sure the polars on the microscope are (1)_________ and you have (2)____________ light
- Uncrossed
- Plane-polarized light
In using Becke line to determine the relief:
Pick a grain that has _________ along the edge of the thin section
sharp edges
In using Becke line to determine the relief:
Focus on _____________ power on the edge of the grain
medium power (or lower in some cases)
In using Becke line to determine the relief:
Shut the ____________ down a bit
Diaphragm
In using Becke line to determine the relief:
Slowly, slightly ____________ the distance between the thin section and the objective
increase (defocus by lowering the stage)
In using Becke line to determine the relief:
You will see 2 thin lines appear along the grain boundary which are?
- Bright or white Becke line
- Dark Becke line
If n grain approximately equals the balsam the bright and dark Becke lines are ______________
colored
Observation of transparent Minerals: Orthoscopic (Crossed)
- Isotropism & Anisotropism
- Interference Colors
- Birefringence
- Twinning
Those w/ uniform physical properties in all directions. It remain dark in all positions even if the stage is rotated.
Isotropism
Those that display colors in varying degrees as the stage is rotated. It produces interference colors.
Anisotropism
For anisotropic minerals only. It is observed w/ reference to the color chart (Michel – Levy Chart)
Interference colors
Vary with the thickness of section, nature of mineral; direction in which the mineral section is cut and the light employed
Interference Colors
Colors displayed by a birefringent mineral in crossed polarized light
Interference Colors
Interference Color
Retardation: 0
Order: _____
Color: Black
zero
Interference Color
Retardation: 0 - 5500
Order: _________
Color/s: ______________
Notes: Neutral Colors are cold, yellow dull
Order: First
Colors: Gray, white, Yellow, Red
Interference Color
Retardation: ________________
Order: Second
Color/s: _______________
Notes: Purest colors, though not totally pure
Retardation: 5500 - 11000
Color/s: Violet through Spectrum to Red
Interference Color
Retardation: __________________
Order: __________________
Color/s: Violet through Spectrum to Red
Note: Have a “fluorescent” appearance
Retardation: 11000 - 16500
Order: Third
Interference Color
Retardation: 16500 and up
Order: Fourth and Higher
Colors: ________________________
Note: Colors become more washed out with increasing retardation
Mostly Greens and Pinks
The term used in describing interference colors.
Order
This maximum colour is often diagnostic of an anisotropic mineral
Birefringence
display simultaneously the maximum and minimum refractive indices.
Birefringence
Formation of rational symmetry intergrowth of 2 or more grains of crystalline species.
Twinning
Form of penetration twinning where two
crystals form as penetration twins.
Carlsbad Twining
common within the plagioclase feldspars, in places where two adjoining twin slabs or lamellae are mutually reversed with respect to each other and every alternate twin ‘plate’ or ‘slab’ has an identical atomic structure
Lamellar Twining
shows two kinds of repeated twinning in thin section, with one set of twins arranged at 90° to the other set.
Cross-hatched twinning
Refers to solid solution which do not have uniform composition.
Zoning
Types of Zoning
Normal Zoning
Reverse Zoning
Oscillatory Zoning
Types of Zoning where the center is more calcic becoming more sodic toward the margin
Normal Zoning
Types of Zoning where the center is more sodic becoming more calcic toward the margin.
Reverse Zoning
Types of Zoning that is normally steplike progressions for more calcic interior to more sodic margins w/ local reversals in adjacent zones
Oscillatory Zoning
it is when a mineral becomes dark parallel to the crosshairs.
Parallel Extinction
Extinct at an angle
with the direction of polars
Inclined/Oblique
planes of mineral to the diagonal; vibration direction is diagonal
Symmetrical
Observation of Transparent Minerals: Conoscopic to get interference figure
- High Power Objective (40x)
- Condenser top lens in
- Analyzer In (Crossed Polars)
- Bertrand lens in
- Accessories In (Gypsum Plate)
Information from Interference Figure
- Number of Optic Axis
- Optic Sign (positive or negative)
- Optic Angle (2v)
- Dispersion
Uniaxial interference Figure
Two arms of the cross form the ____________
Isogyres
Uniaxial Interference Figure
Interference Colors, identical to those on the color chart, increases in order from the Melatope cutwards
Isochromes
Uniaxial Interference Figure
The point where the Isogyres cross is where the optic axis emerges in the interference figure
Melatope
Solution: Alizarine Red S
Mineral: Calcite
Color: ____________
Pink Orange
Solution: Alizarine Red S
Mineral: Aragonite
Color: ____________
Pink Orange
Solution: Alizarine Red S
Mineral: Witherite
Color: __________
Red
Solution: Alizarine Red S
Mineral: Cerussite
Color: __________
Mauve
Solution: Trypan Blue
Mineral: Calcite
Color: __________
Dark Blue
Solution: Trypan Blue
Mineral: Dolomite
Color: __________
Pale Blue
Solution: Silver Chromate
Mineral: Calcite
Color: __________
Red Brown
Solution: Silver Chromate
Mineral: Aragonite
Color: __________
Red Brown
Solution: Copper Nitrate
Mineral: Calcite
Color: __________
Green/ Bluish Green
Solution: Cobalt Nitrate
Mineral: Aragonite
Color: __________
Lilac-Purple
Solution: Harris Hematoxillin Solution
Mineral: Calcite
Color: __________
Lilac
Solution: Meigen
Mineral: Aragonite
Color: __________
Purple
Solution: Meigen
Mineral: Calcite
Color: __________
No Change
Solution: Rhodizonic Acid
Mineral: Witherite
Color: __________
Orange/Red
Solution: Rhodizonic Acid
Mineral: Calcite
Color: __________
No Change
Solution: Tropaeolin
Mineral: Smithsonite
Color: __________
Yellow
Solution: Tropaeolin
Mineral: Magnesite
Color: __________
No Change
Solution: Hydrogen Peroxide - Potassium Hydroxide
Mineral: Ankerite
Color: __________
Orange
Solution: Hydrogen Peroxide - Potassium Hydroxide
Mineral: Siderite
Color: __________
Brown
Solution: Lemberg Hydroxide
Mineral: Calcite
Color: __________
Pale Brown
Solution: Benzidene
Mineral: Rhodochrosite
Color: __________
Blue
Solution: Potassium Ferricyanide
Mineral: Anhydrite / Gypsum
Color: __________
Yellow
Solution: Potassium Ferricyanide
Mineral: Rhodochrosite
Color: __________
Pale Brown
Solution: Potassium Ferricyanide
Mineral: Dolomite
Color: __________
Blue
Solution: Organic Dye Titan Yellow
Mineral: Dolomite
Color: __________
Dark Orange Red
Solution: Organic Dye Eosin Y
Mineral: Dolomite
Color: __________
Dark Pink
Solution: Organic Dye Congo Red
Mineral: Dolomite
Color: __________
Red
Solution: Organic Dye Alizarine Red
Mineral: Dolomite
Color: __________
Lilac
Solution: Feigl Solution
Mineral: Aragonite
Color: __________
Black
Solution: Sodium Cobaltinitrite
Mineral: K-felds
Color: __________
Yellow
Solution: Sodium Cobaltinitrite
Mineral: Plagioclase (Except Albite)
Color: __________
Red
Solution: Kirchberg
Mineral: Ankerite
Color: __________
Gray to Black
Solution: Kirchberg
Mineral: Siderite
Color: __________
little coloring
Solution: Magneson
Mineral: Smithsonite (removed after washing)
Color: __________
Slightly Blue
Solution: Magneson
Mineral: Magnesite (Steps after washing)
Color: __________
Dark Blue
The identification or interpretation of framework mineralogy and textures leading to classification of wallrock as sedimentary, metamorphic or igneous
Petrography
Identification of replacement mineralogy and paragenesis and interepretation in terms of histories of diagenesis, metamorphism, hydrothermal alteration and/or weathering
Petrography
refers to degree of crystallinity, grain size or granularity, and the fabric or geometrical relationship between the constituents of a rock.
Texture
what are the Degree of crystallinity
Holocrystalline
Holohyaline
Hypocrystalline/Merocrystalline
consist wholly of crystals
Holocrystalline
consist entirely of glass
Holohyaline
Contain both crystals and glass
Hypocrystalline/Merocrystalline
Extremely minute, incipient crystals, provided they are birefringent.
Microlites
Smaller, spherical, rod- and hair-like isotropic from.
Crystallite
Fine Grained
Aphanitic or Eucrystalline
Coarse Grained
Phaneritic or Dyscrystalline
Very-fine and undistinguishable under petrographic microscope
Cryptocrystalline
Very-coarsed grained
Pegmatitic
Crystals were bounded completely by crystal faces.
Euhedral / Idiomorphic / Automorphic
Crystals were not bounded by crystal faces.
Anhedral / Allotriomorphic / Xenomorphic
Crystals were partially bounded by crystal faces
Subhedral / Hypidiomorphic
Chiefly minerals are anhedral.
and are common in aplites
Allotriomorphic Granular/ Xenomorphic Granular/ Aplitic / Sugary/ Saccharoidal
chiefly minerals are euhedral and are common in dark hypabyssal rocks or lamprophyres
Panidiomorphic Granular/ Automorphic Granular / Lamprophyric
all faces are present
Hypidiomorphic Granular/ Hypautomorphic Granular/ Granitic
When one mineral is surrounded by another mineral, the enclosing mineral is the _______________
younger
Early crystals are generally ___________ or at least more nearly than those of later crystals
Euhedral
If both large and small crystals occur together, the ________ one are the first to develop
larger
phenocrysts lie in a matrix of glass.
Vitrophyric Texture
the groundmass is a dense intergrowth of quartz and feldspar.
Felsophyric Texture
the groundmass of feldspar are rectangular in form instead of slender lath crystals
Orthopyric Texture
porpyritic texture in which phenocrysts are clustered into aggregates called glomerocrysts or crystal clots. It is common and often included plagioclase and pyroxenes in basic rocks.
Glomeroporphyritic Texture
Process where accumulation of crystals occur by surface tension and fixing by interpretation due to crystal growth
Synneusis
an important consideration in crystal fractionation by crystal settling
Glomerocrysts
Refers to crystals, typically phenocrysts, in an igneous rock which contain small grains of other minerals.
Poikilitic Texture
A variant the Poikilitic texture, is one where random plagioclase laths are enclosed by pyroxene or olivine.
Ophitic Texture
A variant the Poikilitic texture,** plagioclase is larger and encloses the ferromagnesian minerals.**
Sub-ophitic
Angular interstices between feldspars filled with glass instead of pyroxene
Hyalophitic Texture
A genetic term for a border of secondary minerals formed at the margin of a primary grain in an igneous or metamorphic rock.
Corona Texture/ Reaction Rim /
Opacitic Rim
Secondary rim/coronas
Kelyphitic Rim
a textural term indicating that** a crystal occupies the angular space between at least two larger crystals.**
Intergranular Texture
A textural term used to denote that the angular spaces between larger crystals is occupied by glass, or glass and small crystals.
Intersertal Texture
Texture of the groundmass of a holocrystalline igneous rock in which** lath-shaped microlites (typically plagioclase) are arranged in a glass-free mesostasis** and are** generally interwoven in irregular unoriented fashion**.
Pilotaxitic Texture
A texture of extrusive rocks in which the groundmass contains little volcanic glass and consists predominantly of minute tabular crystals, namely, sanidine microlites.
Trachytic Texture
An intergrowth of branching rods of quartz set in a single crystal of plagioclase, neighboring rod of quartz have the same lattice orientation and extinguish together.
Myrmekitic Texture
________________ commonly exhibits a variety of disequilibrium textures in volcanic rocks, especially in orogeny andesites
Plagioclase
common in plagioclase or in pyroxene crystals in extrusive volcanic rocks and is interpreted as the result of mixing processes
Sieve Texture
A process by which a solid solution phase unmixes into two separate phases in the solid
state.
Exsolution
an intimate intergrowth of sodic and potassic feldspar resulting from subsolidus exsolution
Perthitic Texture
an intergrowth arising due to exsolution where potassic feldspar is present as blebs or lamellae within a sodic feldspar.
Anti-PerthicTexture
