A crystal is a solidified form of a substance in which the atoms
are arranged in a definite pattern that is repeated regularly in three dimensions
. Crystals form when saturated
or supersaturated solutions
deposit layer upon layer or a substrate
, initially onto a surface and then upon each other. This process generally forms a solid with remarkable geometric properties
. Because of the mechanics of crystal formation, the slower the crystal forms, the larger and more perfect it will ultimately be.
The beauty and perfection of crystals has long made them prized possessions for human beings. Diamond
s are generally thought to be the most valuable and beautiful crystals. They are composed of a lattice of pure carbon
, as is graphite
, and carbon nanotubes
. The regular structure, and the properties of carbon
, make all of these forms exceptionally strong.
Other fascinating properties of crystals are exploited in electronics
crystals oscillate with sufficient regularity to be used as timepieces, semi-conducting crystals form the basis for modern electronics
. The quantum
properties of the crystal structure allow fascinating electric properties: one can actually make a transistor
from a carbon nanotube
twisted properly. Our increasing understanding of quantum mechanics
and crystals has allowed the development of the laser
and numerous other inventions.
The method in which crystal structure is determined is a process called x-ray crystallography
. It was through these means that the structure of DNA
) was determined by Watson
According to the principle of evolutionary pressure
and selfish gene theory
, some people have offered the supposition that the development of life on earth, and perhaps elsewhere in the universe, began with crystals.