﻿212 Clarke and Diller — Turquois from New Mexico. 



described,* from archaeological and geological points of view ; 

 but, as far as we are able to ascertain, the turquois itself has 

 never been fully analyzed, nor has it been subjected to com- 

 plete microscopic study. Having at our disposal a very full 

 suite of specimens, collected during the summer of 1885 by J. 

 "W". Powell, Director of the U. S. Geological Survey, we have 

 thought it desirable to investigate the subject more thoroughly, 

 and to present our results in such form as to render them 

 readily comparable with the published data concerning tur- 

 quois from other localities. 



The turquois occurs imbedded in its matrix, sometimes in 

 nodules, oftener in seams or veins. It varies in color very 

 widely ; ranging from a pure sky-blue, through many shades 

 of bluish green and apple-green, to dark greens which show no 

 blue whatever. The dark green nodules often shade off to 

 nearly white at the center, sometimes resembling in structure, 

 as Blake has observed, certain varieties of malachite. Many 

 of the specimens are seamed or streaked by limonite, which 

 has been derived from accompanying pyrite; and the latter 

 mineral occasionally is found, bright and unaltered, enclosed 

 completely in masses of clear blue turquois. 



For analysis, three samples of turquois were selected, repre- 

 senting as nearly as possible, the most definite types of the 

 mineral. They may be summarily described, as follows: 



A. Bright blue, faintly translucent in thin splinters. 



B. Pale blue, with a slight greenish cast, opaque and earthy 

 in luster, and of sp. gr. 2*805. Blake gives the density from 

 2*426 to 2*651 for the green variety. 



C. Dark green, opaque. 



A. B. C. 



H 2 



19*80 



19*60 



18*49 



A1 2 3 

 Fe 2 3 



■j 39*53 



36*88 

 2*40 



37-88 

 4*07 



?A 



31-96 



32*86 



28*63 



CuO 



6*30 



7*51 



3*56 



Si0 2 



1*15 



•16 



4-20 



CaO 



•13 



•38 



undet. 



98*87 99*79 99*83 



Anafvsis u A " is not quite complete, for enough material 

 could not be obtained without the destruction of too valuable 

 specimens. The silica in it was due to traces of admixed rock 

 from which the material could not well be perfectly freed. 

 *• C," however, was free from rock ; and the silica in it must be 



* W. P. Blake, this Journal, II, xxv, 227, 1858. J. S. Newberry, " Report of 

 the Exploring Expedition from Santa Fe to the Colorado," etc., 1859; printed, 

 1876. B. Silhman, this Jonrnal, III, xxii, 67, 1881. 



