METALS IN THE GltANlTE. 351 



decompose the mica, or by li3(lrofliioric aiid sulphuric acids. Both the 

 resulting solutions wore examined for heavy metals; and arsenic, antimony, 

 lead, and copper were found in those prepared jjy each of the above meth- 

 ods, Init neither mercury nor gold could be detected in either. Kxperi- 

 ments made with !")() grams of hornblende and mica separated from the rock 

 also failed to d(!tect mercury or gold. Lead almost if not ([uite iilways 

 contains silver, so that tlut presence (if lead in the granitic points to the 

 existence of silver in that rock, although the tests available were, not sufK- 

 ciently delicate to reveal it. Professor Sandberger has actually found silver 

 in the micas of German gi'anites, as well as arsenic, lead, copper, and other 

 metals, lie has also detected zinc in the mica of gneiss.' Silver is rarelv 

 if ever foiiiul in nature unaccompanied by gold, and it is altogether prob- 

 able that micas in which l*rof(!Ssor Sandberger found silver also contained 

 the sister metal. According to Mi'. A. Simundi some of the Idaho granites, 

 collected at long distances from any veins, carry determinable (juantities of 

 gold- 



The granite of Steamboat Springs exhibits considerable variations in 

 texture and mineral composition, as do most other granites. '^Fhis and other 

 phenomena indicate, as Scheerer and others have pointed out, that gi-anite 

 has never been thoroughly fluid and is not uniform in composition. It is 

 therefoi'e far from impossible that specimens of this rock from other points 

 in the region of Steamboat Springs might have shown gold, silver, and zinc. 



Considering that the granite is certainly undergoing decomposition and 

 partial solution by action of the springs and that the metals most abundant 

 in the spring deposits are also found in the granite, it seems to me only 

 reasonable to conclude that from the granite the springs derive the arsenic, 

 antimony, lead, and copper which they bring to the surface. The other 

 metals are found in the deposits in far smaller quantities than those just 

 enumerated. Though not detected in the granite here, all of them except- 

 ing quicksilver are known to occur elsewhere in granite or gneiss. It is 

 also worth noting that silver, gold, and zinc are very frequently associated 

 in natui'e with arsenic, antimony, lead, and copper. The prevalence of this 



' Unteisucbiingeii iiber Erzgiinge, p. 25, 



" Enimous and Becker, Statistics aud Technology of the Precious Metals, p. 54. 



