Chal'cedony (χαλκηδών) occurs only in Re 21:19, being the precious stone with which the third foundation of the wall of the New Jerusalem is garnished. According to Pliny (H. N. 37:8, § 15), chalcedony is a gem resembling the Callais or turquoise, and some have judged it to be a kind of carbuncle or ruby. Salmasius differs from those who make the color of chalcedony to be like that of the carbuncle, and says that they confound τὸν καρχηδόνιον λίθον, which is a species of carbuncle, with τῇ χαλκηδονίῳ; but he confesses that it is by no means clear what stone the ancients called chalcedonius. Pignelius on Revelation (Re 21:19) says that this stone has the color of a pallid lamp, shines in the open air, but is dark in a house, cannot be cut, and has powers of attraction. The etymology of the word is not less doubtful than its meaning. Some derive it from χαλκός, from a belief that it rings like brass when struck. Others have derived it from Χαλκηδών, as though from a locality where it is found, and others from Καρχηδών. (See Braun. de Vest. Hebrews 2, 100:2, p. 525) The Chalcedonius was so called from Chalcedon, and was obtained from the copper mines there; it was a small stone, and of no great value. It is described by Pliny as resembling the green and blue tints which are seen on a peacock's tail or on a pigeon's neck, Mr. King (Antique Gems, p. 8) says it was a kind of inferior emerald, as Pliny understood it. This mineral is supposed by some to be the same that occurs in the Hebrews Scriptures (Ex 28:18) under the name of נֹפֶך, no´phek (translated "emerald"), but this is doubtful. SEE EMERALD. Chalcedony of modern lapidaries is a variety of amorphous quartz, and the distinction between it and agate is not very satisfactorily established. It is harder than flint (spec. grav. 2.04), commonly semi-transparent, and is generally of one uniform color throughout, usually a light brown, and often nearly white (and then termed "white cornelian"); but other shades of color are not infrequent, such as gray, yellow, green, and blue. Chalcedony occurs in irregular masses, commonly forming grotesque cavities, in trap rocks and even granite. It is found in most parts of the world; and in the East it is employed in the fabrication of cups and plates, and articles of taste, which are wrought with great skill and labor, and treasured among precious things. In Europe it is made into snuff-boxes, buttons, knife-handles, and other minor articles. (See Penny Cyclopaedia, s.v. Quartz.) SEE GEM.