THE OSES. (53 



variety of them. As a rule they contain more silicious material, and as a 

 class are probably richer than those of the hill. The difference in value is 

 in part owing to the fact that the deposits are smaller, and although it can- 

 not be said in reference to this district that small deposits in general are 

 richer than large ones, yet it is true that the ores brought to market from 

 Prospect Mountain are more valuable than those from Ruby Hill, inasmuch 

 as a body of ore of considerable size can be made to pay even when the ore 

 is of a low grade, whereas a small one containing the same grade of ore 

 would not yield sufficient metal to defray the expense of mining. A large 

 number of the mines of Prospect Mountain, however, actually contain 

 higher-gi*ade ores than those of Ruby Hill. 



varieties of Prospect Mountain ores. — The ores of the Ruby-Dunderbuig mine 

 closely resemble those of Ruby Hill. The ores of the Eureka Tunnel, on 

 the other hand, which is at present the principal producing mine on Prospect 

 Mountain, differ in several respects from those of Ruby Hill. They are 

 more silicious, an ore occurring frequently which is composed in great part 

 of quartz ; a great deal of the arsenic acid in the yellow carbonate is replaced 

 byantimonic acid; massive blocks of so-called "black metal," a mixture of 

 sulphide and sulphate of lead carrying considerable silver (sometimes as high 

 as $1,000 to the ton), are often met with; carbonate of copper and oxide of 

 manganese are not uncommon, and quartz crystals are frequently found 

 scattered through the ore. 



The ores of the mines on the west slope of the mountain are noted for 

 the relatively larger proportion of gold to silver that they contain. Among 

 the richest of these are the ores of the Silver Connor and Williams mines. 

 The ore from the former of these mines contains but little lead. The ore 

 of the Banner mine is noted for the large amount of silica it contains. It 

 can almost be called a quartz ore. The Dead Broke ore contains consid- 

 erable argentiferous galena and " black metal." 



