148 REPORT UNITED STATES GEOLOGICAL SURVEY. 



Paegasite. — Small particles in quartz. In a dike north of Centre- 



ville. 

 Pegmatite. — At several localities in the vicinity of Georgetown. 



Bear Creek and Gold Hill, in Boulder County. Mount Ouray. 

 Petroleum. — From the oil-wells in Oil Creek Cailon, to the east of 



Canyon City. Smoky Creek, 10 miles south of Golden. 

 Petzite. — In the gold mines of Gold Hill, occurring in narrow seams 



and veins. This mineral occurs also in the other telluride districts. 



Eeported from Lake district. An anlaysis published by Genth* fur- 

 nishes the subjoined result : 



Per cent. 



Quartz 0.62 



Gold 24.10 



Silver 40.73 



Copper trace 



Bismuth 0.41 



Lead 0.26 



Zinc 0.05 



Iron 0,78 



Tellurium 33.49 



100. 44 



Phlogopite. — Mount Princeton; probably a number of the small, splen- 

 dent brown crystals in granites are phlogopite. 



Pickeringite. — This mineral was found by Dr. John Le Conte near 

 Monument Park. It is crystallized in thin needles. An analysis fur- 

 nished B. Goldsmith the following result :t 



Per cent. 



SiOa.. 38.69 



AI2O3. 11.90 



MgO 4.89 



(KaaONaaOj 0.68 



Sand 1.90 



Bydiff. H3O 41.94 



100. 00 



Pitchblende. — See Uraninite. 



Plumbogummite. — On lead and copper minerals of the Dallas lode near 

 Black Hawk. 



Polybasite. — In tabular crystals at the Terrible mine, near George- 

 town, Clear Creek County. 



Prase. — See Quartz. 



Prehnite. — Fair Play, in some of the mines. 



Proustite. — Occurring in the Brown lode, intermixed with galenite. 



Pseudomalachite. — Little Platte River, south of Fair Play. 



PsiLOMELANE. — Seaton Mine, Idaho 5 occurs in small quantities. 



Pyrargyrite. — In the Colorado Central, Terrible, International, Cold 

 Stream mines, at Georgetown, associated with galenite, fahlerz, anc^ 

 sphalerite. In the Brown lode with galenite ; Argentine, Georgetown ; 

 in many of th'e Georgetown silver mines ; in the mines near Fair Play ; 

 in the mines of the San Juan district. Fine crystals occur in the 

 Wheel of Fortune lode. Mount Snefl'els district, San Juan. 



Pyrite. — Pyrite is one of the most widely-distributed minerals of the 

 State. It is found in all the mines of Gilpin County. It occurs in 

 the Empire mining district, in the Gold Hill mines ; in the Trinidad 

 gold mining district ; in the Summit district ; in the San Juan and 

 Lake districts ; in Summit district ; in the mining districts of South 



' * Proc. Am. Phil. Soc, Phil., Vol. XIV, p. 227, 1876. 



tProc. Am. Nat. Sci., Phil., Part III, 1876, p. 333. 



