204 GEOLOGICAL SURVEY OF THE TERRITORIES 



Coppar glance. (CngS.) — Bergen district, near Idaho City, Pleasant 

 View, «&;c. 



Malachite^ (CuO.GOz;) Blue vitriol,, (C11O.SO3+5HO ;) Green vitriol,, 

 (CuO. SO3+7HO.) — Occur in various mines from the decomposition ol 

 the pyrites. 



Fyromorj^hite, (PbO.POs+PbCl.) — Associated with the galenaof va- 

 rious mines near the surface. 



Specular iron ore, (FeO.FcsOa.) — Cache a la Poudre, St. Train's, &c. 



Bed and h'otvn hematite, (FcgOa andEe203+HO.) — Of frequent occur- 

 rence in the vicinity of the coal. 



Coal. — Beds of coal occur all along the flanks of the mountains, 

 but in the property of Mr. Marshall are perhai)s the best exposures 

 Here are no less than nine outcrops. They make their apxoearance at 

 various points along the range as far down as Santa Fe, and are of un- 

 known extent. Albertine coal, or solidified petroleum, is stated by Prof. 

 Denton to occur on White Eiver, in the western part of the Territory. 



Gold. — Occurs in the neighborhood of Central City, in the German 

 lode, and many others. In the Placer diggings. Some beautiful crys- 

 tals attached to cubes of iron X3yrites in the ore from the Pleasant View 

 mine. 



Silver. — In many mines as wire or hair silver, Brown and United 

 States Coin lodes. 



Cerussite, (PbO. CO2.) — Pleasant-View mine. — In small translucent 

 crystals occurring in geodes. 



Anglesite, (PbO. SO3.) — Freedland lode, Trail Run. 



fforn silver, (Ag CI.) — Georgetown, Snake Eiver. 



Enibolite, (AgBr-f-AgCl.) — Peru district, Snake River. 

 • Titanic iron ore, [x Ti^O^-^-y Fe203.) — Quartz Hill, and Russel Gulch, 

 near Central City. 



Micaceous iron ore, (FegOs.) — Elk Creek. In fine crystals like mica. 



Spathic iron ore, (FeO . CO2.) — Eureka and Griffith lodes, &c. 



Stnithsonite, (ZuO . CO2.) — Running lode, Blackhawk, &c. 



Salt, (ISTaCl.) — From Salt Sjirings in South Park, twenty miles south- 

 east of Fairi)lay. Can produce forty thousand pounds jjer diem. 



By characteristic minerals, I mean to include all those that have no 

 commercial value. They furnish proof, in most cases, of the presence 

 of other minerals, of rocks or of formations. Of the characteristic 

 minerals, among the most common are — 



Hydrated oxide of iron, (brown ochre, yellow ochre, bog iron ore, &c.) — 

 Occurs with the coal beds at South Boulder, Golden City, &c., &c., and 

 is frequently regarded as a surface indication of the presence of gold, 

 silver and the precious ores generally. 



Quartz, (SiOs.) — The .most important of the characteristic minerals. 

 Very widely difi'used. Forms the gangue of nearly all the veins of the, 

 precious metals in Colorado, As gangue rock it crops out on the hill 

 sides in white or colored streaks, usually intersecting the planes of strati- 

 fication of the rocks. Uncrystallized, presenting sharp and Jagged edges, 

 and a broken conchoidal uneven fracture, sometimes weathered by the 

 disintegration of the minerals it contained. Pebbles and partially 

 rounded crystals of quartz are abundant in the prairies east of the 

 Rocky Mountains, Avhence they have Iweii carried down, and may be 

 observed hundreds of miles east of the easternmost "hog-back." Indeed, 

 the abundance of these small pebbles of quartz and of the red feldspar 

 is very remarkable, occurring as they do in great quantities on the 

 summits of the little prairie hillocks at such an immense distance from 

 their place of origin. 



