THE COMSTOCK LODE. 79 



one point turned downward, and throughout its whole extent barren portions 

 interrupted the continuity of the silver ore, very much as the non-metal- 

 bearing quartz lay between the bonanzas of the fan systems. The product 

 of this body, $7,500,000, was mined at an immense profit, owing to the 

 extreme concentration of rich ores and their nearness to the surface. The 

 back, or eastern, ore-body was never over six feet thick, and overlapped to 

 the north its larger neighbor. Repeating again the law of the other groups, 

 the richest portions were at the north and near the surface. 



Quartz forms the only gangue in the Comstock lode. Those small masses 

 of carbonate of lime which occur, intermingled with quartz, in the Gold Hill 

 and Hale and Norcross lower levels, are rather to be considered an included 

 mineral of accidental occurrence than as a true gangue. With the excejjtion 

 of small quantities of silver minerals contained in the clay sheets, where they 

 are placed in close contact with the bonanza, the whole silver-tenure of the 

 lode is contained in the bodies of quartz. The ore itself is composed of 

 native gold, native silver, silver glance, stephanite, polybasite, rich galena, 

 occasional pyrargyrite, horn silver, and, with extreme rarity, sternbergite. 

 Intimately associated with these, occur iron and copper pyrites and zinc 

 blende. Of these, pyrargyrite and horn silver are rarities ; polybasite and 

 sternbergite, in recognizable crystals, occupy a few scattered localities ; steph- 

 anite, in defined crystallizations, has been found in nearly every bonanza, but 

 the main body of the ore is a confused semi-crystallized association of native 

 gold and silver, vitreous silver ore, rich galena, copper and iron pyrites, and 

 zinc blende. The following tvi^o analyses, made at the Sheffield Chemical 

 Laboratory of Yale College, are by Mr. W. Gr. Mixter, an assistant of that 

 estabhshment, and Mr. Arnold Hague of this corps. They are of samples 

 from the Savage and Kentuck lower workings of 1869 : 



