186 SILVER-LEAD DEPOSITS OF EUREKA, NEVADA. 



Rearrangement of the ore by water. FrODl tlie disposition of the Ol'e ill a Stratified 



form in the upper part of many of the large ore chambers it is evident that 

 it owes its present position to rearrangement by subterranean water cur- 

 rents. This occurrence has been of comparatively recent date, as the ore 

 has been thus deposited since its oxidation. 



connection of ore bodies with fissures, etc. — Ore bodies are intimately connected with 

 the occurrence of fissures, caves, sediment, and on Ruby Hill with depres- 

 sions in the quartzite. The ore bodies at first sight often seem to have 

 no connection with any fissure or channel through which they could have 

 been filled, but such a connection has been demonstrated in so great a 

 number of cases that it may be presumed to have existed in all. In by 

 far the greater number of instances the fissure has led to the discovery of 

 the body, or the existence of the fissure has been shown in the workings 

 subsequent to the discovery of ore. Sometimes it has been almost oblit- 

 erated by pressure, and in others it has not been revealed by the explora- 

 tions of the miner. 



caves. — Caves are found in many places in the limestone, and no large 

 ore body has been found which had no cave over it, but caves are by no 

 means always accompanied by ore bodies. 



Depressions in the quartzite and ore. — The manner in which the depressions in the 

 quartzite on Ruby Hill occur has been already explained. That large ore 

 bodies should be of frequent occurrence in these depressions is not strange, 

 when it is remembered that the limestone in them was in a shattered and 

 crushed condition, and that the quartzite with its casing of clay served to 

 a certain extent to confine the metal-bearing solutions to the limestone 

 mass, where large quantities of these solutions were probably allowed to 

 settle quietly and deposit ore. 



Relations of the ore bodies to the formations. On Pl'OSpeCt MoUlltaill there are nO 



workings in the neighborhood of the quartzite, and thus far the metallifer- 

 ous zones have been separated by belts of undisturbed limestone and 

 shale. The size of the ore bodies in the mountain has been much smaller 

 than those on Ruby Hill, and the caves have been smaller and less numer- 

 ous. 



