CHEMISTRY. 221 



STOCK to permit of a detailed comparison, such as that given above, but 

 in the absence of proof to the contrary it is probable that it too was depos- 

 ited at the same time. 



Tim= relations of the o«.— During the pcriod in which the field work for the 

 present volume was done, there was but very little ore in sight. What I have 

 seen of ore near the croppings exposed in a few reopened w^orkings, however, 

 and recollections of the streaks of high-grade ore in the "great bonanza," lead 

 to the belief that these rich concentrations were of later origin than the mass 

 of the ore. The quartz in the Consolidated Virginia and California was 

 almost everywhere a crushed, powdery mass, while the thin and persistent 

 veins of black ore running through it were very solid. A somewhat simi- 

 lar relation seems to have existed near the croppings, and it is not impossi- 

 ble that these ores were formed at the expense of others of the more usual 

 kind at a later date, and that they occupy spaces opened in the ore masses 

 bv faulting action. 



Origin of the vein minerals.— It is wcll kuowu that the able aud laborious inves- 

 tigations of Prof. F. Sandbergeri i^^^^ j^jaed greatly to our knowledge of 

 the distribution of the metals in unaltered rocks, and of the reactions by 

 which in many cases they have been concentrated in veins. Though not the 

 first to show that the bisilicates, as well as mica, sometimes carry small 

 quantities of the heavy metals, he has multiplied the known instances so 

 greatly as to establish the frequency of such a composition. In many 

 cases it is an exceedingly complex matter to prove a possible connection 

 between a veia and the surrounding rock, because the minerals present in 

 noticeable quantities are numerous. This is not the case at Washoe, for 

 quartz, silver, gold, and sulphur predominate so greatly over all other ele- 

 ments that if the presence of these is accounted for, the problem may be 

 considered solved, unless the solution offered is inconsistent with the pres- 

 ence of small quantities of calcite, galena, zinc blende, etc., and with the 

 general distribution of pyrite. 



Origin of the quartz and ore.— No chcmical aualysls is necessary to detect a 

 possible origin for the quartz of the Lode. Macroscopical and microscop- 

 ical examinations sufficiently show the enormous destruction of p rimary sili- 



■ Untersuchungeu ilber Erzgange, erstes Heft, 1882. Also, Berg- u. h.-Zeitung, 1877 and 1880. 



