B. Silliman—Turquois of New Mexico. 67 
that marked 1f its upper limit would very well Seger the 
geological locality of the mineral deposit. The strata here, 
owever, have a much more moderate dip than at the og cut 
by the section. 
rude shaft or pit was found to have been sank through 
the beds of dufrenite into a mass of underlying limonite to a 
depth of ten or twelve feet. The irregular bed of dufrenite, 
made up of irregular nodular masses, having from one to eight 
inches of diameter, and incrustations of like varying thickness, 
lies near the surface of the ground, and has an average dept 
of ten or twelve inches, as far as could be determined in the 
presence of a considerable caving in of the old shaft. 
his mineral had been thrown aside in mining as being of 
doubtful character, in the eyes of those who were exploring 
for iron ores, and several tons had been accumulated near the 
mouth of the opening ; but since I first called attention to its 
true character, and although the locality is difficult of access, 
the whole of what was thrown out by the miners has been car- 
ried away and sent to different public institutions and to deal- 
ers in minerals. 
This is, perhaps, the most extensive deposit of this mineral 
yet discovered in the United States 
Washington and Lee University, Tovthaten: Va., May, 1881. 
Art. XIV.—Turquois of New Mexico; by B. StnLiMAn.* 
THE existence of turquois, a comparatively rare gem, 1 
New Mexico, is a fact long known. The chief locality is py 
Mt. Chalchuitl, in Los Cerillos, about twenty-two miles south- 
sta of the ancient town of Santa Fé, the wae: of that terri- 
tory. We are indebted to Professor Wm. P. Blake for our 
first detailed notice of this ancient mine, in an article published 
in the American Journal of Sciencet in 1857. 
It was subsequently visited by Dr. Newberry who mentioned 
it in one of his reports, and also by others. I have lately had 
an opportunity of examining this very interesting Jooaliay since 
it has been laid open in the old workings and thus rendered 
accessible to observation by the recent explorations of Mr. D 
O. Hyde. 
The Cerillos Mountains have recently come into notice ions 
the partial, and as yet superficial, exploration of very numer- 
ous ee veins which are found to intersect them, and which 
ad before the American Association for the Advancement of Science, 
iene oni 1880. 
+ This Jou ronal, 2d Ser., xxv, 27. 
