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LAPIS LAZULI

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Originally appearing in Volume V16, Page 200 of the 1911 Encyclopedia Britannica.
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LAPIS LAZULI , or See also:

azure See also:stone,' a See also:mineral substance valued for decorative purposes in consequence of the See also:fine See also:blue See also:colour which it usually presents. It appears to have been the See also:sapphire of See also:ancient writers: thus See also:Theophrastus describes the u6irOetpos as being spotted with See also:gold-dust, a description quite inappropriate to See also:modern sapphire, but fully applicable to lapis lazuli, for this stone frequently contains disseminated particles of See also:iron-See also:pyrites of gold-like See also:appearance. See also:Pliny, too, refers to the sapphirus as a stone sprinkled with specks of gold; and possibly an allusion to, the same See also:character may be found in See also:Job See also:xxviii. 6. The See also:Hebrew sappir, denoting a stone in the High See also:Priest's breastplate, was probably lapis lazuli, as acknowledged in the Revised Version of the See also:Bible. With the ancient Egyptians lapis lazuli was a favourite stone for amulets and ornaments such as scarabs; it was also used to a limited extent by the Assyrians and Babylonians for See also:cylinder See also:seals. It has been suggested that the Egyptians obtained it from See also:Persia in See also:exchange for their emeralds. When the lapis lazuli contains pyrites, the brilliant spots in the deep blue See also:matrix invite comparison with the stars in the See also:firmament. The stone seems to have been sometimes called by ancient writers Kuavos. It was a favourite material with the Italians. of the Cinquecento for vases, small busts and other ornaments. Magnificent examples of the decorative use of lapis lazuli are to be seen in St See also:Petersburg, notably in the columns of St See also:Isaac's See also:cathedral. The beautiful blue colour of lapis lazuli led to its employment, when ground and levigated, as a valuable pigment known as See also:ultramarine (q.v.), a substance now practically displaced by a chemical product (artificial ultramarine).

Lapis lazuli occurs usually in compact masses, with a finely granular structure; and occasionally, but only as a See also:

great rarity, 1 The Med. Gr. Xaj'oipcov, Med. See also:Lat. lazurius or lazulus, as the names of this mineral substance, were adaptations of the Arab. al-lazward, Pers. lajward, blue colour, lapis lazuli. The same word appears in Med. Lat. as azura, whence O.F. azur, Eng. " azure," blue, particularly used of that colour in See also:heraldry (q.v.) and represented conventionally in See also:black and See also:white by See also:horizontal lines. it presents the See also:form of the rhombic See also:dodecahedron. Its specific gravity is 2.38 to 2.45, and its hardness about 5'5, so that being comparatively soft it tends, when polished, to lose its lustre rather readily. The colour is generally a fine azure or See also:rich See also:Berlin blue, but some varieties exhibit See also:green, See also:violet and even red tints, or may be altogether colourless. The colour is sometimes improved by See also:heating the stone. Under artificial See also:illumination the dark-blue stones may appear almost black.

The mineral is opaque, with only slight translucency at thin edges. Analyses of lapis lazuli show considerable variation in See also:

composition, and this led See also:long ago to doubt as to its homogeneity. This doubt was confirmed by the microscopic studies of L. H. See also:Fischer, F. See also:Zirkel and H. P. J. Vogelsang, who found that sections showed bluish particles in a white matrix; but it was reserved for See also:Professor W. C. See also:Brogger and H. Backstrom, of See also:Christiania, to See also:separate the several constituents and subject them to See also:analysis, thus demonstrating the true constitution of lapis lazuli, and proving that it is a See also:rock rather than a definite mineral See also:species.

The essential See also:

part of most lapis lazuli is a blue mineral allied to See also:sodalite and crystallized in the cubic See also:system, which Bragger distinguishes as lazurite, but this is intimately associated with a closely related mineral which has long been known as hauyne, or hauynite. The lazurite, sometimes regarded as true lapis lazuli, is a See also:sulphur-bearing See also:sodium and See also:aluminium silicate, having the See also:formula: Na4(NaS3AI) Al2 (SiO4)3. As the lazurite and the hauynite seem to occur in molecular intermixture, various kinds of lapis lazuli are formed; and it has been proposed to distinguish some of them as lazurite-lapis and ha-dyne-lapis, according as one or the other mineral prevails. The lazurite of lapis lazuli is to be carefully distinguished from lazulite, an aluminium-See also:magnesium phosphate, related to See also:turquoise. In addition to the blue cubic minerals in lapis lazuli, the following minerals have also been found: a non-ferriferous See also:diopside, an See also:amphibole called, from the See also:Russian mineralogist, koksharovite, See also:orthoclase, See also:plagioclase, a See also:muscovite-like See also:mica, See also:apatite, titanite, See also:zircon, See also:calcite and pyrite. The calcite seems to form in some cases a great part of the lapis; and the pyrite, which may occur in patches, is often altered to See also:limonite. Lapis lazuli usually occurs in crystalline See also:limestone, and seems to be a product of contact See also:metamorphism. It is recorded from Persia, Tartary, See also:Tibet and See also:China, but many of the localities are vague and some doubtful. The best known and probably the most important locality is in See also:Badakshan. There it occurs in limestone, in the valley of the See also:river Kokcha, a tributary to the See also:Oxus, See also:south of Firgamu. The mines were visited by Marco See also:Polo in 1271, by J. B.

See also:

Fraser in 1825, and by See also:Captain See also:John See also:Wood in 1837—1838. The rock is split by aid of See also:fire. Three varieties of the lapis lazuli are recognized by the miners: nili of See also:indigo-blue colour, asmani See also:sky-blue, and sabzi of green tint. Another locality for lapis lazuli is in See also:Siberia near the western extremity of See also:Lake See also:Baikal, where it occurs in limestone at its contact with See also:granite. Fine masses of lapis lazuli occur in the See also:Andes, in the vicinity of Ovalle, See also:Chile. In See also:Europe lapis lazuli is found as a rarity in the See also:peperino of See also:Latium, near See also:Rome, and in the ejected blocks of See also:Monte Somma, See also:Vesuvius. (F. W.

End of Article: LAPIS LAZULI

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