SURVEY OF COLORADO AND NEW MEXICO. 105 



iferoiis galena, brittle silver ore, fahlerz, specular iron, hematite and 

 magnetic pyrites, cerussite and aiiglesite, native gold and silver, horn 

 silver, embolite, (confined chiefly to the neighborhoods of Georgetown 

 ^nd Snake River, 1 believe, as far as yet ascertained,) titanic iron ore, 

 piicaceons iron ore, spathic iron ore, Smithsonite, copper glance, coal 

 aad Albertine coal. These comjjrise the principal ores which I have 

 otiservetl, but time and more thorough search will undoubtedly disclose 

 to the mineralogist, if not to the metallurgist and miner, many as yet 

 hidden treasures. 



Gilpin County and the region about Empire are rated as gold fields, 

 and the values of ores from these and some other districts are given in 

 oun(\es of gold per ton; whereas the adjacent country around George- 

 town^ abounding as it does in argentiferous galena and silver glance, 

 (calldl simply " sulphuret,") has the number of ounc;es silver per ton as 

 its staadard. In some few veins, as the Whale Lode near Idaho City, 

 the va\ues of the gold and silver present in the ore are nearly equal. 



A m\)re detailed specification of the ores follows : 



Iron pyrites, (FeSj.) — Almost universal in the mines. Occurs in 

 cubes frd^n the size of a pin's head to those of an inch on the sides. Also 

 in pentagonal dodecahedra. 



Copiier pyrites, (CuaS+FeSj.) — Is only second to iron pyrites in the 

 frequency \)f its occurrence.* 



Zineblem^, (ZnS.) — Is also very common, especially in the Georgetown 

 region. Fi^e specimens were obtained from the Baker Lode, West Ar- 

 gentine and the Griffith Lode, close by Georgetown. Also from Gilbert's 

 (formerly Colimon wealth Mining Company) Lode, near Nevada City. 



Galena, (PtS.) — Usually argentiferous. In all the lodes in the vicin- 

 ity of Georger\{wu. Contains from one hundred to six hundred ounces 

 silver per ton. 



Brittle silver hre, (Stephanite 5AgS+Sb2S>) — Occurs in the silver mines 

 of Georgetown. \ (Terrible and Brown lodes.) 



Fahlerz, [(I:E»4-4Cu2S) QSg.E^Fe, Cu, Zn and often some Ag and 

 H& = Q^Sb auA As.j — Also in the region around Georgetown. The 

 formula here giv\n are from JSTaumann's Mineralogy. I am not aware 

 that Hghas been discovered in this ore, but as it coincides in its phys- 

 i(;al properties with the ordinary fahlerz, I append the above formula. 



Light ruhy silver\{Proustite,) (SAgS.AsSs); Bark ruby silver, {Py- 

 rargyrite,) (3AgS. SiSo.) — Handsome specimens of these two ores Avere 

 observed intermixedyith the galena from the Brown Lode. Also from 

 Snake River. 



Silver glance, (AgS.V— From the Georgetown neighborhood. Equator 

 and Terrible lodes, i ton of galena, containing much of this ore, 

 was recently sold by a Veutleman of Central City to Professor Hill for 

 $1,900 cash, and the latter realized a profit of $700 from it. 



* Both iron aud copper pyritte of this region contain gold in indefinitely fine particles. 

 The former is, iu fact, the gol\ ore. Where these minerals have been exposed to the 

 action of the weather, they hav\ been decomposed and the gold set free. The valne of 

 the gold in a ton varies from noVhing to five hundred dollars, and even more. I have 

 observed small octahedra of golcipn the crystal faces of iron j)yrites from the Pleasant 

 View mine near Central City. 



t It is somewhat remarkable tha\ these veins of galena generally " pinch up " or grow 

 smaller as the depth increases. I %ke this general statement from the best authority I 

 could obtain on the subject. A gekleman well acquainted with the Georgetown ores 

 informed me that all attempts hitherto to produce lead for the market liad fiiiled from 

 deficiency in the siipiily of galena. Vhis statement, which I give for what it is worth, 

 appears all the more remarkable wheAone compares it with the experience of miners in 

 Freiberg, Przibram, and Clausthal. 



