[Gr. krystallos, ice]
A solid in which atoms are arranged in a specific symmetrical pattern, forming distinct lattices, with definable fixed angles, faces, walls, and interatomic relationships. Examples include ice and many salts.

apatite crystal

In dentistry, the hydroxyapatite crystal typical of calcified tissues; a complex of calcium phosphate and other elements, present in bone and in the cementum, dentin, and enamel layers of teeth. The most dense crystalline pattern is found in enamel, the hardest tissue of the body.

Charcot-Leyden crystal

SEE: Charcot-Leyden crystal

Charcot-Neumann crystal

A spermine crystal found in semen and some animal tissues.

Charcot-Robin crystal

A type of crystal formed in the blood in leukemia.

crystal of hemin

SEE: Hemin.

liquid crystal

A substance that alters its color or changes from opaque to transparent when subjected to changes in temperature, electric current, pressure, or electromagnetic waves, or when impurities are present. Liquid crystals have been used to detect temperature fluctuation in infants and may be divided into two general classes: cholestric, which change color; and nematic, which can change back and forth from transparent to opaque.

spermine crystal

A crystal composed of spermine phosphate and seen in prostatic fluid on addition of a drop of ammonium phosphate solution.