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CHRYSOBERYL—CHRYSOPRASE

He is said to have composed seven hundred and fifty treatises, fragments alone of which survive. Their style, we are told, was unpolished and arid in the extreme, while the argument was lucid and impartial.

See G. H. Hagedorn, Moralia Chrysippea (1685), Ethica Chrysippi (1715); J. F. Richter, De Chrysippo Stoico fastuoso (1738); F. Baguet, De Chrysippi vita doctrina et reliquiis (1822); C. Petersen, Philosophiae Chrysippeae fundamenta (1827); A. Gercke, “Chrysippea” in Jahrbücher für Philologie, suppl. vol. xiv. (1885); R. Nicolai, De logicis Chrysippi libris (1859); Christos Aronis, Χρύσιππος γραμματικος (1885); R. Hirzel, Untersuchungen zu Ciceros philosophischen Schriften, ii. (1882); L. Stein, Die Psychologie der Stoa (1886); A. B. Krische, Forschungen auf dem Gebiete der alten Philosophie (1840); J. E. Sandys, Hist. Class. Schol. i. 149.


CHRYSOBERYL, a yellow or green gem-stone, remarkable for its hardness, being exceeded in this respect only by the diamond and corundum. The name suggests that it was formerly regarded as a golden variety of beryl; and it is notable that though differing widely from beryl it yet bears some relationship to it inasmuch as it contains the element beryllium. In chrysoberyl, however, the beryllium exists as an aluminate, having the formula BeAl2O4, or BeO·Al2O3. The analysis of a specimen of Brazilian chrysoberyl gave alumina 78.10, beryllia 17.94, and ferric oxide 4.88%. The typical yellow colour of the stone inclines in many cases to pale green, occasionally passing into shades of dark green and brown. The iron usually present in the mineral seems responsible for the green colour. Chrysoberyl is often mistaken by its colour for chrysolite (q.v.), and has indeed been termed Oriental chrysolite. In its crystalline forms it bears some relationship to chrysolite, both crystallizing in the orthorhombic system, but it is a much harder and a denser mineral. As the two stones are apt to be confounded, it may be convenient to contrast their chief characters:—

  Chrysoberyl. Chrysolite.
Hardness 8.5 6.5 to 7
Specific Gravity 3.65 to 3.75  3.34 to 3.37
Chemical Composition  BeAl2O4. Mg2SiO4.

Chrysoberyl is not infrequently cloudy, opalescent and chatoyant, and is then known as “cymophane” (Gr. κῦμα, a “cloud”). The cloudiness is referable to the presence of multitudes of microscopic cavities. Some of the cymophane, when cut with a convex surface, forms the most valuable kind of cat’s-eye (see Cat’s-Eye). A remarkable dichroic variety of chrysoberyl is known as alexandrite (q.v.).

Most chrysoberyl comes from Brazil, chiefly from the district of Minas Novas in the state of Minas Geraes, where it occurs as small water-worn pebbles. The cymophane is mostly from the gem-gravels of Ceylon. Chrysoberyl is known as a constituent of certain kinds of granite, pegmatite and gneiss. In the United States it occurs at Haddam, Conn.; Greenfield Centre, near Saratoga Springs, N.Y.; and in Manhattan island. It is known also in the province of Quebec, Canada, and has been found near Gwelo in Rhodesia.  (F. W. R.*) 


CHRYSOCOLLA, a hydrous copper silicate occurring as a decomposition product of copper ores. It is never found as crystals, but always as encrusting and botryoidal masses with a microcrystalline structure. It is green or bluish-green in colour, and often has the appearance of opal or enamel, being translucent and having a conchoidal fracture with vitreous lustre; sometimes it is earthy in texture. Not being a definite crystallized substance, it varies widely in chemical composition, the copper oxide (CuO), for example, varying in different analyses from 17 to 67%; the formula is usually given as CuSiO3 + 2H2O. The hardness (2–4) and specific gravity (2.0–2.8) are also variable. It has recently been suggested that the material may really be a mixture of more than one hydrous copper silicate, since differences in the microcrystalline structure of the different concentric layers of which the masses are built up may be detected. Various impurities (silica, &c.) are also commonly present, and several varieties have been distinguished by special names: thus dillenburgite, from Dillenburg in Nassau, contains copper carbonate; demidoffite and cyanochalcite contain copper phosphate; and pilarite contains alumina (perhaps as allophane). The mineral occurs in the upper parts of veins of copper ores, and has resulted from their alteration by the action of waters containing silica in solution. Pseudomorphs of chrysocolla after various copper minerals (e.g. cuprite) are not uncommon. It is found in most copper mines.

The name chrysocolla (from χρυσός, gold, and κολλα, glue) was applied by Theophrastus and other ancient writers to materials used in soldering gold, one of which, from the island of Cyprus, may have been identical with the mineral now known by this name. Borax, which is used for this purpose, has also been called chrysocolla.

A mineral known as pitchy copper-ore (Ger. Kupferpecherz), and of some importance as an ore of copper, is usually classed as a variety of chrysocolla containing much admixed limonite. It is dark brown to black in colour, with a dull to glassy or resinous lustre, and resembles pitch in appearance. In thin sections it is translucent and optically isotropic, and recent examinations seem to prove that it is a homogeneous mineral and not a mechanical mixture of chrysocolla and limonite.  (L. J. S.) 


CHRYSOLITE, a transparent variety of olivine, used as a gem-stone and often called peridot. The name chrysolite, meaning “golden stone” ( χρυσός and λίθος), has been applied to various yellowish gems, notably to topaz, to some kinds of beryl and to chrysoberyl. The true chrysolite of the modern mineralogist is a magnesium silicate, referable to the species olivine. It is appropriate to call the lighter coloured stones inclining to yellow chrysolite, and the darker green stones peridot. Certain kinds of topaz, from the Schneckenstein in Saxony, are known as Saxon chrysolite; while moldavite, a substance much like a green obsidian, is sometimes called water chrysolite or pseudo-chrysolite.

See Chrysoberyl; Olivine; Peridot.


CHRYSOLORAS, MANUEL [or Emmanuel] (c. 1355–1415), one of the pioneers in spreading Greek literature in the West, was born at Constantinople of a distinguished family, which had removed with Constantine the Great to Byzantium. He was a pupil of Gemistus (q.v.). In 1393 he was sent to Italy by the emperor Manuel Palaeologus to implore the aid of the Christian princes against the Turks. He returned to Constantinople, but at the invitation of the magistrates of Florence he became about 1395 professor of the Greek language in that city, where he taught three years. He became famous as a translator of Homer and Plato. Having visited Milan and Pavia, and resided for several years at Venice, he went to Rome upon the invitation of Bruni Leonardo, who had been his pupil, and was then secretary to Gregory XII. In 1408 he was sent to Paris on an important mission from the emperor Manuel Palaeologus. In 1413 he went to Germany on an embassy to the emperor Sigismund, the object of which was to fix a place for the assembling of a general council. It was decided that the meeting should take place at Constance; and Chrysoloras was on his way thither, having been chosen to represent the Greek Church, when he died suddenly on the 15th of April 1415. Only two of his works have been printed, his Erotemata (published at Venice in 1484), which was the first Greek grammar in use in the West, and Epistolae III. de comparatione veteris et novae Romae.

John Chrysoloras, a relative of the above (variously described as his nephew, brother or son), who, like him, had studied and taught at Constantinople, and had then gone to Italy, shared Manuel’s reputation as one of those who spread the influence of Greek letters in the West. His daughter married Filelfo (q.v.).


CHRYSOPRASE (Gr. χρυσός, gold, and πράσον, leek), a name applied by modern mineralogists to an apple-green variety of chalcedony or hornstone, used as an ornamental stone. The colour is due to the presence of nickel, probably in the form of a hydrous silicate. By exposure to a moderate heat, or to strong light, the chrysoprase becomes paler, or even colourless, but it may regain its colour by absorption of moisture. Chrysoprase is a mineral of rather limited distribution. Most of it comes from the neighbourhood of Frankenstein in Silesia, where it occurs in association with altered serpentine. It is found to a limited extent at Revdinsk, near Ekaterinburg, in the Urals; and it occurs also in India. It is known, too, at several localities