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CERARGYRITE

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Originally appearing in Volume V05, Page 760 of the 1911 Encyclopedia Britannica.
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CERARGYRITE , a See also:

mineral See also:species consisting of See also:silver chloride; an important ore of silver. The name cerargyrite is a See also:Greek See also:form (from it pas, See also:horn, and apyvpos, silver) of the older name hornsilver, which was used by K. See also:Gesner as far back as 1565. The chloro-bromide and bromide of silver were also included under this See also:term until they were distinguished chemically in 1841 and 1842, and described under the names embolite and bromargyrite (or bromyrite) respectively; the chloride then came to be distinguished as chlorargyrite, though the name cerargyrite is often now applied to this alone. Chloro-bromoiodide of silver has also been recognized as a mineral and called iodembolite. All these are strikingly alike in See also:appearance and See also:general characters, differing essentially only in chemical See also:composition, and it would seem better to reserve the name cerargyrite for the whole See also:group, using the names chlorargyrite (AgCI), embolite (Ag(Cl, Bl)), bromargyrite (AgBr) and iodembolite (Ag(Cl, Br, I)) for the different isomorphous members of the group. They are cubic in See also:crystallization, with the See also:cube and the See also:octahedron as prominent forms, but crystals are small and usually indistinct; there is no cleavage. They are soft (H = 21) and sectile to a high degree, being readily cut with a See also:knife like horn. With their resinous to adamantine lustre and their translucency they also See also:present somewhat the appearance of horn; hence the name hornsilver. The See also:colour varies somewhat with the chemical composition, being See also:grey or colourless in chlorargyrite, greenish-grey in embolite and bromargyrite, and greenish-yellow to See also:orange-yellow in iodembolite. On exposure to See also:light the colour quickly darkens. The specific gravity also varies with the composition: for the pure chloride it is 5'55, and the highest recorded for an iodembolite is 6-3.

The hornsilvers all occur under similar conditions and are often associated together; they are found in metalliferous See also:

veins with native silver and ores of silver, and are usually confined to the upper oxidized parts of the lodes. They are important ores of silver (the pure chloride contains 75.3 % of silver), and have been extensively See also:mined at several places in See also:Chile, also in See also:Mexico, and at Broken See also:Hill in New See also:South See also:Wales. The chloride and chlorobromide have been found in several Cornish mines, but never in very large amounts. (L. J.

End of Article: CERARGYRITE

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