Society & Culture & Entertainment Education

What is a Crystal?

In the movie "A Few Good Men", when Jack Nicholson asked Tom Cruise, "Are we clear?" he replied "Crystal".
What this means is that his understanding is as clear as crystal.
So in general, the word crystal refers to a large extent, clarity.
The word crystal is defined as transparent quartz occurring in nature.
It is either colorless or slightly tinged.
The unique molecular structure in crystal gives that arrangement and pattern extending in various symmetrical and three spatial dimension solid.
There are basically seven types of crystal forms (ref.
GemologyOnline.
com).
The following describes each system and natural minerals in which the crystal system can be found.
The axes used here refer to the formation of a solid body with one cross center.
1.
Cubic - Isometric The cube is composed of 6 square faces at 90 degree angles to each other.
Each face intersects one of the crystallographic axes and is parallel to the other two.
This system is also called isometric with 3 perpendicularly right angular intersected lines.
The center of the intersection is equi-distant to the end of each line.
The ends of each line (there are six) will form that cube.
Diamond, Garnet, Rhodolite and Spinel all have this crystal form.
2.
Tetragonal The tetragonal system also has three axes that all meet at 90°.
It differs from the isometric system in that the perpendicular axis is longer than the two horizontal axes which are the same length.
Zircon has this crystal form.
3.
Hexagonal In the hexagonal system we have additional axes, which give the crystals six sides.
Three of these are equal in length and meet at 60° to each other.
The C or vertical axis is at 90° to the shorter axes.
Mineralogists sometimes divide this into two systems, the hexagonal and the trigonal, based on their external appearances.
The hexagonal structure can found in aquamarine, benitoite, beryl, emerald, heliodor and morganite.
4.
Trigonal Again, the trigonal system is a subsystem of the hexagonal.
Most gem references will list these as hexagonal.
The popular minerals with this crystal form include amethyst, citrine corundum, ruby, sapphire, tourmaline, eudialyte and quartz.
5.
Orthorhombic In this system there are three axes, all of which meet at 90° to each other.
However, all the axes are a different length.
This crystal system can be found in alexandrite, andalusite, chrysoberyl, Iolite, peridot, tanzanite, topaz and varisite.
6.
Monoclinic The above crystal systems all have axes sides that meet at 90°.
In the monoclinic system all the axes are different lengths.
Two of the axes meet at 90°, but the third one does not.
Monoclinic crystal structure can be found in azurite, diopside, feldspar, kunzite and nephrite.
7.
Triclinic In this system all the axes are different lengths and none of them meet at 90°.
Turquoise has this crystal structure.
In the real world, natural crystal was a rarity to begin with, and now has become even rarer through human excavation.
Therefore the crystal we have today is actually a man-made glass product.
As the technology of glass manufacturing advances, crystals of various sizes and shapes can be produced with a very high degree of clarity and light refraction as analogues to isometric patterns in the natural crystal.
Today's crystal is basically made by the same processes used in making other glass products.
The formula may vary in order to produce high transparent optical glass which is what most of the crystals are made of.
Also the equipment may differ due to the fact that making crystalrequires larger blocks of molten glass.
Most importantly, the down stream machining of the glass blocks is extremely critical and technically demanding.
It takes many different types of cutting, beveling, lathing, grinding, and polishing to achieve the desired isometric shape.
We absolutely must appreciate the crystalawards that are available and we enjoy today.
They are product of a combination of high end technology as well as fine craftsmanship.


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