﻿Clarice and Diller — Turquois from New Mexico. 215 



quois, which showed that the fibrous structure is directly 

 across the vein perpendicularly to its walls. Small fissures, 

 running into or across the veins, have the fibers of turquois 

 arranged perpendicularly along their sides just as serpentine 

 arranges itself along fissures in olivine. Sometimes the fissures 

 are minute and curved ; but the resulting arrangement does 

 not simulate the radial fibrous or spherulitic structure de- 

 scribed by Bucking* as found in the turquois of California, 

 Nevada and elsewhere. 



The perpendicular arrangement of the turquois fibers along 

 fissures crossing the vein, indicates that the mineral may have 

 been derived from the alteration of another substance with which 

 the vein was formerly filled. We would suppose, of course, 

 that the original vein material was itself a phosphate ; and the 

 only one after which turquois is known to be pseudomorphous 

 is apatite ; a species which not infrequently occurs in veins. 

 The opinion that the turquois has resulted from such an 

 alteration is favored by the presence of other alteration pro- 

 ducts, to be noted in considering the composition of the country 

 rock in which the turquois is found. It is also suggested by 

 Hermann's analysis of blue oriental turquois, in which the 

 equivalent of 3*41 per cent of calcium phosphate was actually 

 determined, f 



The rock in which the veins of turquois occur is described 

 by Blake as "a granular porphyry, yellowish, gray, or white 

 in color, porous and earthy in texture. It decomposes rapidly 

 by weathering, and very much resembles a sandstone." In the 

 collection made by Major Powell there are several good ex- 

 amples of the rock penetrated by the turquois. It is a fine- 

 grained, reddish, felclspathic rock, mostly fresher than that 

 described by Blake, and it has a microgranitic aspect. It con- 

 tains numerous particles of biotite and pyrite, with stainings of 

 oxide of iron. The hand specimens look as though they had 

 been crushed, and the fissures thus formed so filled as to pro- 

 duce irregular veins and nodules. The veins are small, and 

 mostly composed of turquois, in which are imbedded a few 

 scales of biotite, particles of pyrite, and considerable quartz 

 and oxide of iron. Scales of biotite are found abundantly 

 in the iron -stained cavities, as well as in the solid portions 

 of the rock. Some specimens of rock, containing much 

 pale blue turquois of earthy texture, have been completely 

 kaolinized, and a partial analysis of the kaolin gave the fol- 

 lowing results : 



* Zeitsch. far Kryst. und Min., ii, p. 163. 

 f See Dana's System of Mineralogy, p. 581. 



Am. Jour. Scl— Third Series, Yol. XXXII, No. 189.— September, 1886. 

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