ENDLicH.] CATALOGUE OF COLORADO MINERALS. 149 



and Nortli Parks. Mostly it is auriferous and associated with chalco- 

 pyrite. Found both massive and crystallized. Massive in the Leavitt, 

 Briggs, Kansas, Bobtail, and other mines near Central. Large bodies 

 of it occur in the Mammoth, Gunnell, Grand Army, and other lodes 

 near Central. Cubes in combination with the pentagonal dodecahe- 

 dron are found in the Winnebago, Mack, Dallas, Kansas, Grand Army, 

 Gunnell, and other mines at Central. Crystallized and massive in the 

 mines of Silver Hills, Buckskin, Idaho ; in the Tenth Legion mine at 

 Empire ; in the Elk Mountain district. Cubes are found in the Gran- 

 ite of the Mount Princeton group, on Eagle Eiver in the mines of 

 Summit district. Cubes of four to five inches edge in the Phillips 

 mine. Cubes and octahedra, simple and in combination in the San 

 Juan district. Pentagonal dodecahedra in the Bobtail and Briggs at 

 Central. Octahedra at the head of the Uncompahgre. Octahedra on 

 Anthracite Creek. 



Radiated pyrite (possibly MarTcasite). — Smoky Hill Eiver ; P urgatory, 

 Apishpa Creek. 

 Pykolusite. — Massive at Buckskin and in Silver Hills. Eureka Gulch 



near Howards ville, San Juan. 

 Pyromorphite. — Freeland lode. Trail Creek. 



Pyroxene. — Near Fair Play. In a number of localities in younger 

 volcanic and metamorphic rocks. Crystals in the basalts of Southern 

 San Luis Valley. 

 Pyrrhotite. — Malachite lode, Jefferson County, l^evada district, 



Gilpin County. 

 Quartz. — Occurs massive in some of the very coarse-grained granites. 

 Many of the quartz- veins are almost or totally devoid of ore, in which 

 case the quartz is generally milk-white and pure. 



Crystals, very pretty quartz crystals, small ; occur on Quartz Hill 

 near Central. The Bobtail, Gunnell, Briggs, and other mines near 

 Central furnish good, small crystals. In the Eosita lodes and in some 

 of the mines of Georgetown. On East Eiver ; in the mines of the Elk 

 mountain district; Iowa Gulch; Sopris Peak; head of Anthracite 

 Creek. Good crystals with many combinations of the pyramidal faces 

 are found on Topaz Butte. Dihexahedral crystals occur in the por- 

 phyry of the Sangre de Cristo range and in the rhyolite near Uncom- 

 pahgre Peak. At Spanish Peaks. 



Smoky quarts. — The locality on Bear Creek near Pike's Peak has 

 become well known on account of its smoky quartz crystals associated 

 with green orthoclase. Large crystals, reaching over a foot in length, 

 are there found, in cavities of the granite. Crystals are also found 

 on Elk Creek and on the Upper Platte. 

 Rosy quartz. — Occurs at many localities in Colorado, in the granites. 

 Good specimens can be obtained from the head of Eoaring Fork. 

 Found, also, near Clear Creek, and on Bear Creek. 

 Amethyst. — Small crystals at Nevada and neighboring localities ; 

 on Eock Creek ; Clear Creek County ; on the summit of the range 

 east of the Animas. 

 Agate. — Fine specimens, lined with amethyst, on the summit of the 

 range east of the Animas. Cloudy, of white and gray color, in 

 the lower trachytic formations of the Uncompahgre group; in 

 various forms, cloudy, banded, laminated, and variegated, at the 

 Los Pinos agency. In South Park, in the drift ; in the Lower 

 Arkansas Valley; on the Frying Pan ; throughout Middle Park; 

 on the Lower Gunnison and adjacent regions. 

 Moss-agate. — Below the Uncompahgre, near Grand Eiver. 



