200 B. Silliman—Mineralogical Notes. 
partly in the lower portion of Yavapai County, and partly 
n the northern portion of Maricopa County. Within this 
area are numerous veins of gold-bearing quartz carrying 
lead and sometimes a little copper or perhaps both at the 
same time. I have become familiar with the mineralogical 
character of these veins through Mr. G. A. Treadwell: and 
Mr. Edward Farley, owner of some of the mines which have 
furnished the most interesting species of this area, has prepared 
for me a sketch map on which the localities are laid down with 
sufficient accuracy for identification by reference to the Gov- 
ernment map. 
Farley’s “Collateral Mine,” about twenty miles northeast of 
Vulture, is perhaps the most interesting locality of vanadinite 
in this area. The vein is about four and a half feet wide, 
crystals of vanadinite arranged in threads and in stellar tufts, 
usually not over a line in thickness, but occasionally opemns 
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mimetite, but give no arsenical reaction, and I failed to obtain 
