Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Crystal shopping experience:
1. Compare - without doubt the biggest advantage that the Crystal offers shoppers today is the ability to compare thousands of Crystal at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.
2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about
3. Testimonials - don't know anybody that has bought a Crystal? Wrong! If the Crystal is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about Crystal then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
5. Reputation - Never heard of the company selling Crystal? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Crystal and build up a picture of their reputation for sales, returns, customer service, delivery etc.
6. Returns - still worried that even after all of the above your Crystal wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your Crystal then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the Crystal site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Crystal, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Crystal, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
image:Unknown Quartz crystal 67.JPG crystal
image:Bismuth_crystal_macro.jpg hopper crystal crystals, a metal that easily forms large single crystals grown from solution by Saint-Gobain for the megajoule laser of
Commissariat à l'Énergie Atomique.
In
chemistry and mineralogy, a
crystal is a
solid in which the constituent
atoms, molecules, or
ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions.
The word
crystal originates from the Greek word "Krystallos" meaning
clear ice, as it was thought to be an especially solid form of
water. The word once referred particularly to quartz, or "rock crystal".
Most metals encountered in everyday life are polycrystal. Crystals are often symmetrically intergrown to form
Crystal twinning.
Crystal structure
Which crystal structure the
fluid will form depends on the chemistry of the fluid, the conditions under which it is being solidified, and also on the
Ambient temperature . The process of forming a crystalline structure is often referred to as
crystallization.
While the cooling process usually results in the generation of a crystalline material, under certain conditions, the fluid may be frozen in a noncrystalline state. In most cases, this involves cooling the fluid so rapidly that atoms cannot travel to their
Bravais lattice sites before they lose mobility. A noncrystalline material, which has no
long-range order, is called an
amorphous, vitreous, or glassy material. It is also often referred to as an
amorphous solid, although there are distinct differences between solids and glasses: most notably, the process of forming a glass does not release the
latent heat of fusion. For this thermodynamic reason, many scientists consider glassy materials to be
viscosity liquids rather than solids, although this is a
controversy; see the entry on
glass for more details.
Crystalline structures occur in all classes of materials, with all types of
chemical bonds. Almost all metallic bond exists in a polycrystalline state; amorphous or single-crystal metals must be produced synthetically, often with great difficulty.
ionic bond crystals can form upon solidification of salts, either from a
molten fluid or when it condenses from a solution.
Covalently bonded crystals are also very common, notable examples being diamond, silica, and
graphite. Polymer materials generally will form crystalline regions, but the
lengths of the
molecules usually prevents complete crystallization. Weak Van der Waals forces can also play a role in a crystal structure; for example, this type of bonding loosely holds together the hexagonal-patterned sheets in
graphite.
Most crystalline materials have a variety of
crystallographic defects. The types and structures of these defects can have a profound effect on the properties of the materials.
Other meanings and characteristics
Since the initial discovery, made in 1982 by Dan Shechtman, the acceptance of the concept and the word
quasicrystal have lead the International Union of Crystallography to redefine the term crystal to mean 'any solid having an essentially discrete diffraction diagram', thereby shifting the essential attribute of crystallinity from position space to Fourier space. Within the family of crystals one distinguishes between traditional crystals, which are periodic on the atomic scale, and aperiodic crystals which are not. This broader definition adopted in 1996 reflects the current understanding that microscopic periodicity is a sufficient but not a necessary condition for crystallinity.
While the term "crystal" has a precise meaning within materials science and
solid-state physics, colloquially "crystal" refers to solid objects that exhibit well-defined and often pleasing geometric shapes. In this sense of the word, many types of crystals are found in nature. The shape of these crystals is dependent on the types of molecular bonds between the atoms to determine the structure, as well as on the conditions under which they formed.
snows, diamonds, and common
salt are common examples of crystals.
Some crystalline materials may exhibit special electrical properties such as the
ferroelectric effect or the
piezoelectricity. Additionally,
light passing through a crystal is often Refraction or bent in different directions, producing an
array of colors;
crystal optics is the study of these effects. In periodic
dielectric structures a range of unique optical properties can be expected as described in photonic crystals.
Crystallography is the scientific study of crystals and crystal formation.
Crystalline rocks
Animal shell with
calcite crystalsInorganic matter, if free to take that physical state in which it is most stable, always tends to crystallize. Crystalline
rock (geology) masses have
consolidated from aqueous solution or from molten
magma. The vast majority of igneous rocks belong to this group and the degree of crystallization depends primarily on the conditions under which they solidified. Such rocks as
granite, which have cooled very slowly and under great pressures, have completely crystallized, but many lavas were poured out at the surface and cooled very rapidly; in this latter group a small amount of
amorphous or glassy matter is frequent. Other crystalline rocks, the
evaporites such as rock salt,
gypsum and some limestones have been deposited from aqueous solution, mostly owing to
evaporation in
arid climates. Still another group, the
metamorphic rocks which includes the
marbles,
mica-schists and
quartzites; are recrystallized, that is to say, they were at first fragmental rocks, like limestone,
shale and
sandstone and have never been in a molten condition nor entirely in solution. The high temperature and pressure conditions of metamorphism have acted on them erasing their original structures, and inducing recrystallization in the solid state.
See also
References
External links
- Introduction to Crystallography and Mineral Crystal Systems
- Crystallographic Teaching Pamphlets
- Crystal Lattice Structures
- The Giant Crystal Project - documenting the largest crystals and crystal aggregates known to exist
image:Unknown Quartz crystal 67.JPG crystal
image:Bismuth_crystal_macro.jpg hopper crystal crystals, a metal that easily forms large single crystals grown from solution by Saint-Gobain for the megajoule laser of
Commissariat à l'Énergie Atomique.
In chemistry and
mineralogy, a
crystal is a
solid in which the constituent
atoms,
molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions.
The word
crystal originates from the Greek word "Krystallos" meaning
clear ice, as it was thought to be an especially solid form of water. The word once referred particularly to quartz, or "rock crystal".
Most metals encountered in everyday life are
polycrystal. Crystals are often symmetrically intergrown to form Crystal twinning.
Crystal structure
Which
crystal structure the fluid will form depends on the
chemistry of the fluid, the conditions under which it is being solidified, and also on the
Ambient temperature . The process of forming a crystalline structure is often referred to as
crystallization.
While the cooling process usually results in the generation of a crystalline material, under certain conditions, the fluid may be frozen in a noncrystalline state. In most cases, this involves cooling the fluid so rapidly that atoms cannot travel to their Bravais lattice sites before they lose mobility. A noncrystalline material, which has no long-range order, is called an
amorphous, vitreous, or
glassy material. It is also often referred to as an amorphous solid, although there are distinct differences between solids and glasses: most notably, the process of forming a glass does not release the latent heat of fusion. For this thermodynamic reason, many scientists consider glassy materials to be
viscosity liquids rather than
solids, although this is a controversy; see the entry on glass for more details.
Crystalline structures occur in all classes of materials, with all types of
chemical bonds. Almost all
metallic bond exists in a polycrystalline state; amorphous or single-crystal metals must be produced synthetically, often with great difficulty.
ionic bond crystals can form upon solidification of salts, either from a molten fluid or when it condenses from a solution. Covalently bonded crystals are also very common, notable examples being
diamond, silica, and
graphite.
Polymer materials generally will form crystalline regions, but the lengths of the molecules usually prevents complete crystallization. Weak
Van der Waals forces can also play a role in a crystal structure; for example, this type of bonding loosely holds together the hexagonal-patterned sheets in graphite.
Most crystalline materials have a variety of crystallographic defects. The types and structures of these defects can have a profound effect on the properties of the materials.
Other meanings and characteristics
Since the initial discovery, made in 1982 by
Dan Shechtman, the acceptance of the concept and the word quasicrystal have lead the International Union of Crystallography to redefine the term crystal to mean 'any solid having an essentially discrete diffraction diagram', thereby shifting the essential attribute of crystallinity from position space to Fourier space. Within the family of crystals one distinguishes between traditional crystals, which are periodic on the atomic scale, and aperiodic crystals which are not. This broader definition adopted in 1996 reflects the current understanding that microscopic periodicity is a sufficient but not a necessary condition for crystallinity.
While the term "crystal" has a precise meaning within materials science and
solid-state physics, colloquially "crystal" refers to solid objects that exhibit well-defined and often pleasing geometric shapes. In this sense of the word, many types of crystals are found in nature. The shape of these crystals is dependent on the types of molecular bonds between the atoms to determine the structure, as well as on the conditions under which they formed.
snows,
diamonds, and common
salt are common examples of crystals.
Some crystalline materials may exhibit special electrical properties such as the ferroelectric effect or the piezoelectricity. Additionally, light passing through a crystal is often Refraction or bent in different directions, producing an array of colors;
crystal optics is the study of these effects. In periodic dielectric structures a range of unique optical properties can be expected as described in photonic crystals.
Crystallography is the scientific study of crystals and crystal formation.
Crystalline rocks
Animal shell with
calcite crystals
Inorganic matter, if free to take that
physical state in which it is most
stable, always tends to crystallize. Crystalline
rock (geology) masses have
consolidated from
aqueous solution or from molten magma. The vast majority of
igneous rocks belong to this group and the degree of crystallization depends primarily on the conditions under which they solidified. Such rocks as granite, which have cooled very slowly and under great pressures, have completely crystallized, but many
lavas were poured out at the surface and cooled very rapidly; in this latter group a small amount of amorphous or glassy matter is frequent. Other crystalline rocks, the evaporites such as
rock salt, gypsum and some
limestones have been deposited from aqueous solution, mostly owing to
evaporation in
arid climates. Still another group, the
metamorphic rocks which includes the marbles, mica-schists and quartzites; are recrystallized, that is to say, they were at first fragmental rocks, like limestone, shale and
sandstone and have never been in a molten condition nor entirely in solution. The high temperature and pressure conditions of
metamorphism have acted on them erasing their original structures, and inducing recrystallization in the solid state.
See also
References
External links
- Introduction to Crystallography and Mineral Crystal Systems
- Crystallographic Teaching Pamphlets
- Crystal Lattice Structures
- The Giant Crystal Project - documenting the largest crystals and crystal aggregates known to exist
Crystal - invigorate your senses
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Please visit my main site while I re-update your favourite. www.crystal-escort-cardiff.co.uk
