CHEMISTRY. 219 



Bullion has also been produced at the Justice to the south, and from the 

 veins on Cedar Hill to the north In the Virginia and Gold Hill mines, 

 and on Cedar Hill, the gangue is quartz, only occasional masses of calcite 

 of insignificant size having been encountered. South of the Overman, on 

 the other hand, the gangue is largely calcite. 



The quartz of Cedar Hill carries free gold, alloyed, of course, with a 

 little silver. Certain stringers from the main Lode and the "west vein" of 

 the CoMSTOCK, as that portion lying to the west of the great horse in Vir- 

 ginia City, above the line at which the two fissures join, is usually called, 

 are of the same character. The Justice ore was argentiferous, but very 

 "base," carrying large quantities of galena, zinc blende, etc. The ore 

 bodies on the main Lode in Virginia and Gold Hill, which have yielded 

 almost all of the bullion extracted, may profitably be considered as of two 

 classes. The greater portion of the bullion has been derived from minerals 

 disseminated in the quartz in microscopic particles. Ore of this kind is 

 often distinguisliable from ban-en quartz by bluish stains, but not always. 

 The quality, and even the presence of ore, can in many cases only be told 

 by assay, and superintendents who have taken part in the mining opera- 

 tions almost from their commencement do not hesitate to confess that their 

 judgment of the quartz is often at fault. The behavior of this ore in amal- 

 gamation shows that its silver contents is mainly due to argentite. Its gold 

 contents constitutes from one-quarter to one-half its total value. Near the 

 outcroppings many bunches of other ores occurred, such as stephanite, 

 polybasite, ruby silver, etc. These were in some cases accompanied by 

 relatively lai'ge quantities of galena and zinc blende. In the great Consol- 

 idated Virginia and California bonanza, several streaks or veins of very 

 rich black silver ores, said to be mainly stephanite, occurred. These were 

 separated from the surrounding oi"e-bearing quartz very sharply, as if of 

 later origin 



Pyrite is found everywhere, both in the country rock and in the ore 

 disseminated in small crystals. It is less frequent in the quartz than in the 

 country rock, but it is especially abundant in the east country, opposite the 

 ore bodies. It also occurs with frequency in the diorite west of and near 

 the Lode. In all these cases it forms but a small portion of the mass — say 



