70 B. Silliman—Turquois of New Mexico. 
The stone used for these hammers is the hard and tough 
hornblende andesite, or propylite, which forms the Cerro 
d’Oro and other Cerillos hills) With these rude .tools and 
without iron and steel, using fire in place of pice oti these 
patient old workers managed to break down and remove the 
incredible masses of chess baceas rocks hice form. the 
mounds already describe 
That considerable quantities of the turquois were obtained 
can hardly be questioned. We know that the ancient Mexicans 
attached great value to this ornamental stone, as the Indians 
do to this day. The familiar tale of the gift of large and costly 
turquois by Montezuma to Cortez for the Spanish crown, as 
narrated by Clavigero in his history of Mexico, is evidence of 
this high estimation. It is not known that any other locality 
in America has furnished turquois in any quantity—the only 
other place thus far reported outside of Los Cerillos meine that 
near Columbus District in mht discovered by Mr. 
Clayton; and this is not yet wo 
The origin of the turquois of Los Cerillos in view of late 
observations is not doubtful. Chemically it is a hydrous 
aluminum phosphate. Its blue color is due to a variable 
uantity of copper oxide derived from associated rocks. I find 
that the Cerillos turquois contains 3°81 per cent of this metal. 
Neglecting this constituent, the formula for turquois requires : 
Phosphoric acid 32°6, alumina 47 ‘0, water 205=100°?. 
Evidently the decomposition of the feldspar of the trachyte 
furnishes the alumina, while the apatite, or phosphate of lime, 
rock, furnished the phosphoric acid, A little copper ore is 
diffused as a constituent of the veins of this region, and hence 
the color which that metal imparts. 
crystalline rocks of the district ipa the line of volcanic fis- 
ures. In fact there are, in a northerly direction, other places, 
