|1.||an impure microcrystalline form of quartz consisting of a variegated, usually banded chalcedony, used as a gemstone and in making pestles and mortars, burnishers, and polishers. Formula: SiO2|
|2.||a playing marble of this quartz or resembling it|
|3.||(US), (Canadian) printing Also called: ruby (formerly) a size of printer's type approximately equal to 5½ point|
|[C16: via French from Latin achātēs, from Greek akhatēs]|
|agate (āg'ĭt) Pronunciation Key
A type of very fine-grained quartz found in various colors that are arranged in bands or in cloudy patterns. The bands form when water rich with silica enters empty spaces in rock, after which the silica comes out of solution and forms crystals, gradually filling the spaces from the outside inward. The different colors are the result of various impurities in the water.
(Heb. shebo), a precious stone in the breast-plate of the high priest (Ex. 28:19; 39:12), the second in the third row. This may be the agate properly so called, a semi-transparent crystallized quartz, probably brought from Sheba, whence its name. In Isa. 54:12 and Ezek. 27:16, this word is the rendering of the Hebrew cadcod, which means "ruddy," and denotes a variety of minutely crystalline silica more or less in bands of different tints. This word is from the Greek name of a stone found in the river Achates in Sicily.