THE ORES. 59 



though it may exist. It is not likely, however, that if it formed at any 

 time it could remain loug in quantity uncombined with carbonic acid in the 

 presence of waters carrying so much of that compound. Wad has been 

 observed in the Phoenix mine and in some other localities; also other forms 

 of manganese in different places, and nickel is said to have been found, 

 though no specimens have been obtained. 



Miners- classification of ore. — The ores of the district are not accurately classi- 

 fied by the miners, but receive names indicative of their most striking char- 

 acteristics and the popular idea of the corresponding composition. It may 

 be well to describe some of the more important varieties. Most of the ore 

 has a reddish or yellowish color, due to the presence of oxide of iron, chloro- 

 arsenate, or molybdate of lead. The shades of color vary according to the 

 predominance of one or the other of these minerals . and the quantity of 

 earthy material mixed with them. One of the principal kinds of ore is com- 

 posed of a hydrated oxide of iron mixed with some sulphate and carbonate 

 of lead and containing intermingled grains and lumps of undecomposed 

 galena. This ore is often called "red carbonate." It usually carries about 

 equal values of gold and silver, from $25 to $50 of each per ton, though 

 sometimes the gold is considerably in excess. Another variety is the "yellow 

 carbonate." This term is applied in general by the miners to any ore of a 

 yellow color which contains lead. It belongs particularly, however, to a 

 very characteristic ore, which is a mixture of the hydrated oxide of iron 

 with the sulphate and chloro-arsenate of lead in varying proportions. The 

 ratio of the silver to the gold in this ore is not at all uniform; sometimes 

 one metal, sometimes the other, being in excess. The value of both metals 

 does not usually exceed $100 per ton. Another variety of "yellow car- 

 bonate" is that which owes its color to the molybdate of lead mixed through 

 it. As the molybdate of lead usually carries but little silver and less gold, 

 this ore is not very rich unless it contains other minerals bearing the 

 precious metals. The so-called "sulphuret ore" of the miners is an almost 

 pure crystallized carbonate of lead. It is grayish in color,' and consists of 

 aggregated crystals of cerussite. It is sometimes quite rich in silver, assay- 

 ing as high as $125, but like all the lead ores proper is poor in gold. There 

 are several varieties of red ore, consisting principally of the hydrated oxide 



