•268 MICA AND ITS USES. 



and united in two parts by means of a transparent glue, in which he incor- 

 porated a coloring matter m harmony with the stone he meant to represent, 

 brilliant red for carbuncle and green for emerald. He concealed the line 

 of junction of the two parts by means of the setting, and to avoid giving 

 rise to suspicion he set them in gold, which was not allowed except in the 

 •case of real precious stones. In this way this magnificent workman de- 

 ceived everybody, even the lapidaries. However, the fraud was at last 

 ■discovered, and Zocolino took refuge in flight. It appears that this person 

 had a peculiar disposition for fraud, for he turned his attention afterward 

 to the fabrication of counterfeit money, and ended by being condemned to 

 ■death. An examination of the objects adorned with precious stones that 

 were executed in the middle ages, shows that the process described by Car- 

 dan was not unfrequently employed," — Globe Democrat. 



MICA AND ITS USES. 



Mica, from the Latin "to shine," is composed of silex, alumina, and 

 potash. It is found in almost every country on the globe — America, Swit- 

 zerland, Siberia, Norway, Bohemia, and Eussia. Siberia and the United 

 States probably furnish the best and largest specimens. It occurs in gran- 

 ite and quartz, also in rubellite, green tourmaline, feldspar, lepodolite, and 

 several other minerals. Itls one of the constituents of granite, gneiss, and 

 mica schist, talc-slate, etc. It sometimes occurs in granular limestone, and 

 rarely in lava, dolomite, and magnetic iron ores. According to Dana, mica 

 is usually in thinly foliated plates or scales ; color from white, through green, 

 yellowish and brownish shades, to black; with a pearly lustre, transparent 

 or translucent; before the blowpipe infusible, but becomes opaque white. 

 There are a number of varieties. That in which the scales are arranged in 

 plumose form is called plumose mica ; that in which the leaves or scales 

 liave a transverse cleavage is called prismatic mica. The crystals are chiefly 

 rhombic, or six-sided, though not always. The cleavage of mica is highl}' 

 perfect, and, according to Professor Henry, it can be split or divided into 

 leaves 250,000 to the inch. It shows a tendency to associate with quartz, 

 :and in the mines recently discovered in New Mexico a coarse quartz mixed 

 with fine white crystal formation is the sign of the mica mine. Many de- 

 posits or veins have been discovered in San Juan during the winter, but a 

 very small per cent, carry mica of a merchantable quality; the cleavage is 

 generally transverse, or foreign coloring matter enters into it to such an ex- 

 tent that it is worthless for market. The uses of mica are various. Dia- 

 mond dust, with -which court dames and our own American ladies powder 

 their hair, is ground mica. The costly French silver mouldings are 

 €ast from ground mica. The wonderful showers of diamonds I have 

 witnessed in the scenic plays of the " White Pawn " and the " Black Crook," 

 at Niblo's, were mica scales. As a lubricator it is perfection. Mixed with 



