Crystal growth and defects can influence mineral properties. Crystals grow through nucleation and growth processes that depend on factors like temperature, pressure, and concentration changes. Point defects like vacancies or impurities, and planar defects like twins or dislocations influence properties. Color arises from electron transitions in d-orbitals of transition metals or between ions. Magnetic properties depend on whether electrons' magnetic moments cancel or add. Crystal structures and defects thus underlie important mineral characteristics.
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Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
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Metals in prosthodontics/certified fixed orthodontic courses by Indian dental...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
Rocks and Minerals
A mineral is a naturally occurring inorganic compound with a unique chemical structure and physical properties.
A rock is a solid, stony mass composed of a combination of minerals or other organic compounds.
For example, quartz and feldspars are minerals, but when formed together, they make a rock, granite”
To determine if an Earth rock is a mineral, it should exhibit the following characteristics
Naturally occurring
Inorganic
Can be represented by a chemical formula
Crystalline structure
Solid
Most minerals form by inorganic processes but some, identical in all respects to inorganically formed minerals, are produced by organic processes
Transparency describes how well light passes through a mineral sample
There are three degrees of transparency: transparent, translucent, and opaque.
Habit of a mineral may be define as the size and shape of the crystal, and the structure of form shown by the crystal.
1. Accicular minerals showing needle like crystal. E.g. natrolite
2. Fibrous minerals showing an aggregate of long thin fibers. E.g. Asbestos
3. Tabular minerals showing bladed habit occur as small knife blades. E.g. Kyanite
4. Granular minerals which occur as aggregate of equidimensional grains. E.g. chromites
5. Pisolitic minerals which occur as aggregate of rounded grains of a pea size. E.g. oolite
6. Columnar minerals showing columnar crystal. E.g. tourmaline
Minerals strength determines how easy the mineral breaks or deforms when exposed to stress.
Reaction with Acid. Some minerals, especially carbonate minerals, react visibly with acid. (Usually, a dilute hydrochloric acid [HCl] is used.)
When a drop of dilute hydrochloric acid is placed on calcite, it readily bubbles or effervesces, releasing carbon dioxide
It's a complete ppt of the chapter "THE SOLID STATE" explaining all the concepts with diagrams and full theory .
Hope it help you for your exams....!!!!!
Mineralogy
Definition of mineral, mineralogy, Importance of study of minerals: rock forming and ore forming minerals. Different methods of study of minerals. Study of minerals by physical identification method and their physical properties.Forms and Habits, Colour, Streak, Lustre, Fracture, Cleavage, Hardness, Specific Gravity, Degree of Transparency, Special Properties Determination of Physical properties of following minerals: Feldspar, Quartz, Flint, Jasper, Olivine, Augite, Hornblende, Muscovite, Biotite, Asbestos, Chlorite, Kyanite, Garnet, Talc, Calcite. Study of ore forming minerals such as Pyrite, Hematite, Magnetite, Amethyst, Galena, Pyrolusite, Graphite, Magnetite, and Bauxite, Coral reefs.
Importance of Mineral, Chemical Composition of Earth Crust, Structure of Silicates
Ceramic materials are inorganic, non-metallic materials made from compounds of a metal and a non metal. Ceramic materials may be crystalline or partly crystalline.
The word ceramic comes from the Greek word keramiko of pottery" or for pottery from keramos
Rocks and Minerals
A mineral is a naturally occurring inorganic compound with a unique chemical structure and physical properties.
A rock is a solid, stony mass composed of a combination of minerals or other organic compounds.
For example, quartz and feldspars are minerals, but when formed together, they make a rock, granite”
To determine if an Earth rock is a mineral, it should exhibit the following characteristics
Naturally occurring
Inorganic
Can be represented by a chemical formula
Crystalline structure
Solid
Most minerals form by inorganic processes but some, identical in all respects to inorganically formed minerals, are produced by organic processes
Transparency describes how well light passes through a mineral sample
There are three degrees of transparency: transparent, translucent, and opaque.
Habit of a mineral may be define as the size and shape of the crystal, and the structure of form shown by the crystal.
1. Accicular minerals showing needle like crystal. E.g. natrolite
2. Fibrous minerals showing an aggregate of long thin fibers. E.g. Asbestos
3. Tabular minerals showing bladed habit occur as small knife blades. E.g. Kyanite
4. Granular minerals which occur as aggregate of equidimensional grains. E.g. chromites
5. Pisolitic minerals which occur as aggregate of rounded grains of a pea size. E.g. oolite
6. Columnar minerals showing columnar crystal. E.g. tourmaline
Minerals strength determines how easy the mineral breaks or deforms when exposed to stress.
Reaction with Acid. Some minerals, especially carbonate minerals, react visibly with acid. (Usually, a dilute hydrochloric acid [HCl] is used.)
When a drop of dilute hydrochloric acid is placed on calcite, it readily bubbles or effervesces, releasing carbon dioxide
It's a complete ppt of the chapter "THE SOLID STATE" explaining all the concepts with diagrams and full theory .
Hope it help you for your exams....!!!!!
Mineralogy
Definition of mineral, mineralogy, Importance of study of minerals: rock forming and ore forming minerals. Different methods of study of minerals. Study of minerals by physical identification method and their physical properties.Forms and Habits, Colour, Streak, Lustre, Fracture, Cleavage, Hardness, Specific Gravity, Degree of Transparency, Special Properties Determination of Physical properties of following minerals: Feldspar, Quartz, Flint, Jasper, Olivine, Augite, Hornblende, Muscovite, Biotite, Asbestos, Chlorite, Kyanite, Garnet, Talc, Calcite. Study of ore forming minerals such as Pyrite, Hematite, Magnetite, Amethyst, Galena, Pyrolusite, Graphite, Magnetite, and Bauxite, Coral reefs.
Importance of Mineral, Chemical Composition of Earth Crust, Structure of Silicates
Ceramic materials are inorganic, non-metallic materials made from compounds of a metal and a non metal. Ceramic materials may be crystalline or partly crystalline.
The word ceramic comes from the Greek word keramiko of pottery" or for pottery from keramos
Metals in prosthodontics/dental crown &bridge course by Indian dental academyIndian dental academy
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
This slide is all about crystal structure such as unit cell, simple cubic unit cell, body-centered unit cell, and face-centered unit cell. Also, I explained Crystal defects such as line defects, planar defects, and point defects.
undamentals of Crystal Structure: BCC, FCC and HCP Structures, coordination number and atomic packing factors, crystal imperfections -point line and surface imperfections. Atomic Diffusion: Phenomenon, Fick’s laws of diffusion, factors affecting diffusion.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Multi-source connectivity as the driver of solar wind variability in the heli...
Lec 10 - Geol217 Fall2021 - OAR.pdf
1. Crystal Growth & Defects:
Chapter 10 - Klein & Dutrow, 2007. Manual of Mineral Science, 23rd Edition.
Chapter 5 - Nesse, 2018. Introduction to Mineralogy, 3rd Edition.
Chapter 5 - Wenk & Bulakh, 2004. Minerals
2. Outline
• Crystal growth
• Growth by ?
• Growth from ?
• Mineral properties related to mineral growth
• Crystal defects
• Point, line, plane defects
• Mineral properties related to defects
3. Crystal growth: Growth from ?/Growth by ?
Igneous minerals from melt
Metamorphic minerals from solids
Sedimentary minerals
from solution
from vapor
from solid- hydrosphere
interaction
from solid- atmosphere
interaction
Supersaturation
by changing
concentration
by changing
temperature
by changing
pressure
4. Crystal growth
• Nucleation from solution
• Ex: NaCI dissolved in water
• by changing the concentration
• Evaporation → more Na+ and Cl- per unit volume →
supersaturation
• Slow evaporation → few crystals with characteristic shapes,
sharing a crystallographic orientation
• Rapid evaporation → many small nuclei form, randomly oriented
crystals
• by changing the temperature
• Hot water will dissolve slightly more NaCI than cold water.
• Lowering the temperature → supersaturation
• by changing the pressure
• The higher the pressure the more NaCI water can hold in solution
• Lowering the pressure → supersaturation
Klein & Dutrow, 2007
5. Crystal growth: Nucleation from solution
Application: solution mining
http://www.goldenpotash.com/project/solution-mining/ Google Earth
6. Crystal growth
• In magma, many ions and ionic groups exist in an uncombined state.
• Crystal nucleation and growth in a cooling magma are the result of two competing tendencies:
• Thermal vibrations that tend to destroy the nuclei of potential minerals
• Attractive forces that tend to aggregate atoms (and/or ions) into crystal structures
• As the temperature falls, the temperature effect diminishes, which allows the attractive forces to
dominate.
7. Crystal growth
http://www.snowcrystals.com
Fumarole on Kīlauea Volcano, Hawai‘i. (USGS)
• As the vapor is cooled, the dissociated atoms or molecules combine, eventually locking
themselves into a crystalline solid.
Ex: the formation of snowflakes from
air saturated with water vapor
Ex: the formation of sulfur crystals at the
base of fumaroles, or volcanic vents, from the
condensation of sulfur-rich gas
9. Crystal growth
• Most nuclei will not develop into larger
crystals because in a solution saturated
with respect to Na+ and Cl- ions, there is
also a tendency for nuclei to be
redissolved.
• These tiny crystals have a very large
surface area compared to their volume
• A large surface area implies that there are
many atoms on the outer surface of the
crystal with unsatisfied chemical bonds.
• If a nucleus is to survive, it must grow
rapidly enough to reduce its surface
energy (expressed as the ratio of surface
area to volume) and, consequently, its
solubility.
Monroe et al., 2007
10. Crystal growth
• When a nucleus reaches a critical size
through rapid deposition of further layers
of ions, it will have a high chance of
surviving and growing into a larger crystal.
• The energy of such a surface is lowered
when an atom attaches itself to it, and
the amount of energy released by such an
attachment depends on where the
attachment occurs.
• the energy of attachment is
• greatest at the corners
• intermediate at the edges
• and least in the middle of faces
11. Crystal growth
• The rate of growth determines which faces will become
prominent on a crystal; the slowest growing faces are manifest
in a crystal’s external morphology.
• {111} faces
• parallel to layers of Na+ and Cl−
• have a net positive or negative charge
• high surface energy (unsatisfied or distorted chemical
bonds )
• growth should be very fast because the greatest energy
reduction is achieved there
• each successive layer will be thicker and smaller
• {001} faces
• equal numbers of Na+ and Cl− exposed
• electrically neutral and lack a net electrical attraction for
cations or anions
• growth rate is relatively slow
12. Crystal growth: Mineral properties related to mineral growth
• Different atomic arrangements underlie different crystal planes or crystallographic directions.
• Properties that depend on direction in the crystal are called vectorial properties.
Vectorial properties
Discontinuous
vectorial properties
pertain only to certain planes or
directions within the crystal
Ex: growth rate, solution rate, and
cleavage
Continuous
vectorial properties
vary continuously with direction
within the crystal
Ex: hardness, thermal expansion,
electrical conductivity, and velocity
of light
13. Crystal growth: Discontinuous vectorial properties
• Cleavage
• takes place along those planes across which
the weakest bonding forces exist.
Cleavage planes are generally
the most widely spaced and
the least densely populated
Biotite
Graphite Diamond
14. Crystal growth: Discontinuous vectorial properties
• Growth rate
• Dendrites are an extreme
case of prevalent apex and
edge growth.
• The unique crystals
resemble a branching
plant, hence the name
‘‘dendrites’’.
• Ex: native gold, copper,
and silver and in
pyrolusite
Silver Copper
Halite
15. Crystal growth: Discontinuous vectorial properties
• Solution rate
• If a crystal is treated with a chemical solvent that attacks
it, the faces are etched or pitted.
• The shape of these pits is regular and depends on
• the structure of the crystal
• the face being etched
• the presence of chemical substitutions and inclusion
• the nature of the solvent
Etching
?
16. Crystal growth: Continuous vectorial properties
• Hardness
• Kyanite is strongly anisotropic, and its
hardness varies depending on
crystallographic direction, which is
considered an identifying
characteristic.
• The Mohs scale hardness of kyanite is
• ~4.5–5 when scratched in the
direction of [001]
• ~6.5–7 when scratched
perpendicular to this direction
17. Crystal growth: Continuous vectorial properties
• Thermal expansion
• Most minerals have unequal coefficients of
thermal expansion in different directions,
leading to poor resistance to thermal shock and
easy fracturing with heating or cooling.
• SiO2 glass
• an irregular internal structure
• more resistant to thermal shock
• Quartz
• crystalline
• less resistant to thermal shock
Wu et al., 2019
18. Crystal growth: Continuous vectorial properties
• Velocity of light
• The velocity of light in all transparent crystals, with the exception of those that are
isotropic, varies continuously with crystallographic direction.
19. Crystal defects
• Crystals are rarely flawless, and natural as well as
synthetic crystals commonly contain imperfections.
• Such imperfections affect
• growth rate
• crystal morphology
• basic properties of crystalline materials, such as:
• strength
• conductivity
• mechanical deformation
• color
• Imperfections in crystal structures are generally
classified by the dimension of their geometry as:
• point defects
• line defects
• plane defects
Defects
Point defects
Schottky
defects
Frenkel
defect
Impurity
defect
Line defects
Edge
dislocations
Screw
dislocations
Plane defects
Lineage
structures
Stacking
fault
Twinning
20. Crystal defects: Point defects – 0D
Point
defects
Schottky
defects
Frenkel
defect
Impurity
defect
Interstitial Substitutional
• Schottky defects
• vacancy defects
• Frenkel Defects
• mislocation defects
• Interstitial defects
• foreign ions that occupy
sites not normally used
• Substitution defects
• foreign ions that
substitute for one of the
normally present ions
21. Crystal defects: Line defects – 1D
• Slip does not involve simultaneously breaking all chemical bonds along the
slip plane.
• Rather, slip propagates through a crystal so that bonds are broken only along
a line defining the leading edge of the slip surface.
• The edges of the propagating slip surface, where chemical bonds are being
broken, are known as dislocation lines.
Line
defects
(Dislocations)
Edge
dislocations
dislocation line (DL) is
perpendicular to the Buergers vector
and
moves to the right (parallel to the
Buergers vector) as deformation
progresses.
Screw
dislocations
dislocation line (DL) is
parallel to the Buergers vector
and
moves to the back (perpendicular to the
Buergers vector) as deformation
progresses
22. Crystal defects: Plane defects – 2D
• Lineage structures
• In ideally perfect crystals,
• short-range + long-range order
• In less ideal (more real) crystals,
• Crystal made of a mosaic of domains that differ only
slightly in orientation.
• Each block in the mosaic has short-range order, but
the whole crystal lacks long-range order.
• This arrangement results in irregular zones or lines
of edge dislocations spaced at irregular intervals.
• These zones (or lines) will be irregular planar features
along which ions (or atoms) have an irregular
structural environment. These zones of irregularity
are known also as lineage structures. The structures
on either side of such lineages are slightly
misoriented with respect to each other.
23. Crystal defects: Plane defects – 2D
• Stacking fault
• a regular sequence of layers is
interrupted by an improperly
positioned layer
or
• one of the layers required in a
perfect crystal is missing
24. Crystal defects: Plane defects – 2D
• During the growth of a mineral, offsets to the atomic arrangement of the structure may occur that are
nonrandom. This results in the development of relatively common intergrowth patterns of well-
formed crystals (as well as anhedral grains).
Intergrowths
Different
compositions
Epitaxis
Same
composition
Parallel
growth
Symmetrical intergrowth
(Twinning)
Parallel intergrowth of barite crystals Two quartz crystals twinned across a mirror plane
25. Crystal defects
• Epitaxis
• Although the two compositionally distinct
intergrown crystals will tend to have
different structures (and unit cell sizes),
there are planes in their internal structures
where there is a good fit (or the least
amount of misfit) between them.
• This similarity in substrate reduces the
energy required for nucleation allowing for
such preferential overgrowth.
26. Crystal defects: Plane defects – 2D
• Parallel growth
• An aggregate of similar crystals with their crystallographic axes and faces parallel to each other is
called a parallel growth. Such aggregates, although they may at first appear to represent several
crystals, are a single crystal because the internal atomic structure remains unchanged in
orientation throughout the specimen.
27. Crystal defects: Plane defects – 2D
• Twinning
• a symmetrical intergrowth of two or
more crystals of the same
substance.
• The two or more individual crystals
of the twinned aggregate are related
by a symmetry element that is
absent in the original (untwinned)
crystal.
• The twin law that describes the twin
operation includes:
• specification of the twin
operation and
• identification of the
crystallographic plane or axis
associated with the twinning.
• Twin plane is never
parallel to a plane of
symmetry.
• The twin law is usually
expressed as “reflection
on {hkl}” or “twins on
{hkl},”
• Twin axis can never be an
axis of even rotation (two-,
four-, six-fold) if the twin
rotation involved is 180°.
• Twin law for a typical 180°
rotation is usually
expressed as “2-fold
rotation on [uvw]”
28. Crystal defects: Plane defects – 2D
Twins
Contact twins:
have a regular
composition surface
separating the two
individuals.
Penetration twins:
are made up of
interpenetrating
individuals having an
irregular composition
surface
(100) Contact twin in gypsum [001] penetration twin in orthoclase
Twins
Simple twins:
composed of just two
twin segments.
Multiple twins:
composed of three or more
segments repeated by the
same twin law.
Polysynthetic
twins
Cyclic twins
Polysynthetic twinning in plagioclase
by repeated reflection on {010}
Cyclic twinning in rutile by
repeated reflection on {011}
29. Crystal defects: Mineral properties related to defects
• Origin of color
• Origin of magnetic properties
30. Crystal defects: Origin of color
Color
• Color is the response of the eye to the visible light range of the electromagnetic spectrum.
• Color depends on the wavelengths that the mineral does not absorb.
31. Crystal defects: Origin of color
Origin of color
Crystal field transitions and Charge
transfer transitions
depend on having electrons on specific elements
Crystal field
transitions
electronic transitions to
higher energy level of
partially filled d orbitals of
the same ion
Charge transfer
transitions
electronic transitions to
higher energy levels on
adjacent ions
Color centers
depend on having electrons mislocated
Electron
color centers
Electron trapped in a vacant
site in a crystal
Hole
color centers
Electron is missing from its
normal location
33. Crystal defects: Origin of color
Crystal Field Transitions
• electronic transitions between partially filled d orbitals of transition elements.
34. Crystal defects: Origin of color
Factors influencing the color produced
by crystal field interactions are:
• the presence of a specific transition
element
• its oxidation state (valence), which
determines the number of electrons
in 3d orbitals
• the geometry of the site in which the
transition metal is housed,
(octahedral, tetrahedral, etc.)
• the strength of the crystal field
(charges on anions, distortion of
coordination polyhedra, etc.)
Peridot
Fe2+ in octahedral
Chrysoberyl
Fe3+ in octahedral
Almandine
Fe2+ in cubic
Fe Cr
Emerald
Cr3+ replace Al3+ in octahedral
There is a covalent component to the bonding
The absorption peaks are at lower energy
Ruby
• Cr3+ replace Al3+ in octahedral
• bonding is ionic
35. Crystal defects: Origin of color
Molecular orbital (charge transfer) transitions
• absorb electromagnetic radiation when
valence electrons are bumped to higher
energy levels on adjacent ions.
• Charge transfers may be:
• between two cations
• between an anion and a cation
• between two anions
X2+ + Y3+ ⇌ X3+ + Y2+
36. Crystal defects: Origin of color
Color centers
Electron
color centers
Electron trapped
in a vacant site in
a crystal
Hole
color centers
Electron is
missing from its
normal location
Electron color centers
Hole color centers
37. Crystal defects: Origin of color
Origin of color
Crystal field transitions and Charge
transfer transitions
depend on having electrons on specific elements
Crystal field
transitions
Electronic transitions to
higher energy level of
partially filled d orbitals of
the same ion
Charge transfer
transitions
Electronic transitions to
higher energy levels on
adjacent ions
Color centers
depend on having electrons mislocated
Electron
color centers
Electron trapped in a vacant
site in a crystal
Hole
color centers
Electron is missing from its
normal location
38. Crystal defects: Origin of magnetic properties
Origin of magnetic properties
• Magnetism derives from a property
of electrons called the magnetic
moment that results from their
spinning and orbiting motions.
• The sum of all the magnetic
moments of all the atoms in a
mineral gives it magnetism.
39. Crystal defects: Origin of magnetic properties
• Not attracted to even very powerful magnets;
in fact they are slightly repelled by them
Diamagnetic minerals
• Weakly attracted to strong magnets
• become magnetized in an external magnetic
field, but lose their magnetization when the
external field is removed
Paramagnetic minerals
Paramagnetism
Diamagnetism
40. Crystal defects: Origin of magnetic properties
Ferrimagnetism
• can retain magnetization for long periods of time
• Ferrimagnetism differs from ferromagnetism in that some atoms/ions in adjacent structural
sites have antiparallel magnetic moments
• The term antiferromagnetism is applied to materials in which antiparallel spins completely
cancel to yield zero net magnetic moment. It can be considered a special case of
ferrimagnetism.
Ferromagnetic – ferrimagnetic minerals
Ferromagnetism Antiferromagnetism
43. • Otálora, F., & García-Ruiz, J. (2014). Nucleation and growth of the Naica giant gypsum crystals.
Chemical Society Reviews, 43(7), 2013–2026. https://doi.org/10.1039/C3CS60320B
• Veritasium. (2021, January 27). These Pools Help Support Half The People On Earth.
https://www.youtube.com/watch?v=YMDJA4UvXLA
• Nikkei Asia. (2018, March 14). How to make pure, synthetic quartz.
https://www.youtube.com/watch?v=lzHqhNoyx2o
• Yancoal Canada. (2016, April 29). Yancoal Canada—Southey Potash Project.
https://www.youtube.com/watch?v=EHz_iRjWGPU
• FuseSchool - Global Education. (2015, December 4). Extraction Of Salt | Acids, Bases & Alkali’s |
Chemistry | FuseSchool. https://www.youtube.com/watch?v=_nPrlrS6g10
• uclaphysicsvideo. (2013, November 9). Paramagnetism and Diamagnetism.
https://www.youtube.com/watch?v=u36QpPvEh2c
• Uniclass Content. (2015, May 27). Concentration of Ores—Class 12.
https://www.youtube.com/watch?v=8oTdCGj334U
GEOL217