In this publication measurements of interfacial angles of crystals are used to classify and identify chemical substances.

When the atoms are relatively similar in size, the atom exchange method usually happens, where some of the atoms composing the metallic crystals are substituted with atoms of the other constituent.

Many agates are hollow, since deposition has not proceeded far enough to fill the cavity, and in such cases the last deposit commonly consists of drusy quartz, sometimes amethystine, having the apices of the crystals directed towards the free space so as to form a crystal-lined cavity or geode.

These are composed of strontium sulfate crystals, which do not fossilize, and take the form of either ten diametric or twenty radial spines.

Furthermore, in very small crystals a large fraction of the atoms are located at or near the surface of the crystal ; relaxation of the surface and interfacial effects distort the atomic positions, decreasing the structural order.

Upon sporulation, B. thuringiensis forms crystals of proteinaceous insecticidal δ-endotoxins ( called crystal proteins or Cry proteins ), which are encoded by cry genes.

High end crystals, cubic zirconia simulated diamonds, and some semi-precious stones are used in place of precious stones.

The atoms in molecules, crystals, metals and diatomic gases — indeed most of the physical environment around us — are held together by chemical bonds, which dictate the structure and the bulk properties of matter.

However, metallic bonds are more collective in nature than other types, and so they allow metal crystals to more easily deform, because they are composed of atoms attracted to each other, but not in any particularly-oriented ways.

In addition to their microscopic structure, large crystals are usually identifiable by their macroscopic geometrical shape, consisting of flat faces with specific, characteristic orientations.

Common crystals include snowflakes, diamonds, and table salt ; however, most common inorganic solids are polycrystals.

Not all solids are crystals.

These are grouped into 7 crystal systems, such as cubic crystal system ( where the crystals may form cubes or rectangular boxes, such as halite shown at right ) or hexagonal crystal system ( where the crystals may form hexagons, such as ordinary water ice ).

By volume and weight, the largest concentrations of crystals in the earth are part of the Earth's solid bedrock.

Many living organisms are able to produce crystals, for example calcite and aragonite in the case of most molluscs or hydroxylapatite in the case of vertebrates.

For example, selenite crystals in excess of 10 meters are found in the Cave of the Crystals in Naica, Mexico.

Covalently bonded crystals are also very common, notable examples being diamond, silica, and graphite.

Crystals of BPO < sub > 4 </ sub > can also precipitate from the flowing glass on cooling ; these crystals are not readily etched in the standard reactive plasmas used to pattern oxides, and will result in circuit defects in integrated circuit manufacturing.

Because of their highly ordered and repetitive structure, crystals give diffraction patterns of sharp Bragg reflection spots, and are ideal for analyzing the structure of solids.

For historical reasons, many point defects, especially in ionic crystals, are called centers: for example a vacancy in many ionic solids is called a luminescence center, a color center, or F-center.

When these crystals are exposed to radiation, the dysprosium atoms become excited and luminescent.

The tables include those for the classification angles, refractive indices, and melting points of the various types of crystals.

Within each chapter an effort has been made to group together those crystals with similar structures.

In fact, all specific heats vanish at absolute zero, not just those of crystals.

In building and for countertops, the term " granite " is often applied to all igneous rocks with large crystals, and not specifically to those with a granitic composition.

Liquid crystals ( LCs ) are a state of matter that have properties between those of a conventional liquid and those of a solid crystal.

Since lyotropic liquid crystals rely on a subtle balance of intermolecular interactions, it is more difficult to analyze their structures and properties than those of thermotropic liquid crystals.

This anisotropy makes flows of liquid crystals behave more differentially than those of ordinary fluids.

Conversely, those same crystals will change about 0. 1 % of their static dimension when an external electric field is applied to the material.

A formalism has been worked out for those piezoelectric crystals, for which the polarization is of the crystal-field induced type, that allows for the calculation of piezoelectrical coefficients from electrostatic lattice constants or higher-order Madelung constants.

Except for the Al – Li – Cu system, all the stable quasicrystals are almost free of defects and disorder, as evidenced by x-ray and electron diffraction revealing peak widths as sharp as those of perfect crystals such as Si.

Very rarely will it form distinct, well individualized crystals showing a square-like cross-section, like those found at the Jeffrey Mine in Asbestos, Quebec, Canada.

Low-frequency crystals, such as those used in digital watches, are typically cut in the shape of a tuning fork.

The ice crystals in contrails are much smaller than those in naturally-occurring cirrus clouds, as they are around 0. 001 millimeters to 0. 1 millimeters in length.

On the SNES, the buttons used are those that match the colors of the crystals ( A B X and Y ), while on GBA, the D-pad is used, matching the crystals positions on the screen, although the SNES colors remain.

Some habits of a mineral are unique to its variety and locality: For example, while most sapphires form elongate barrel-shaped crystals, those found in Montana form stout tabular crystals.

For single crystal work, the crystals must be much larger than those used in X-ray crystallography.

For three dimensional photonic crystals, various techniques have been used including photolithography and etching techniques similar to those used for integrated circuits.

The developer selectively reduces silver halide crystals in the emulsion to metallic silver, but only those having latent image centres created by action of light.

Igneous textures include those that refer to the size of the mineral grains ; vitreous-glassy, without crystals, aphanitic-grains not visible, phaneritic-grains clearly visible, and porphyritic-large grains in a finer matrix.

( 2 ) Complex crystals: separate the phonon-glass from the electron crystal using approaches similar to those for superconductors.