ENDLicH.] CATALOGUE OF COLORADO MINERALS. 137 



Alum. — Mount Vernon. 



Aluminite. — Mount Vernon. 



Amalgamite. — Occurring in connection with coloradoite in the Key- 

 stone Mine, Boulder County. 



Amber. — (One specimen found near the head of Cherry Creek. This 

 may, however, be one of the numerous resins occurring in the Hgnitio 

 coal. They resemble amber, but differ in composition. See VVheel- 

 erite.) 



Amethyst. — See Quartz. 



Amianthite. — North Boulder Creek. 



Amphibolitb. — Occurs at numerous localities in the dikes traversing 

 granite. Small acicular crystals can be obtained from the porphyritio 

 and sanidiuitic trachytes. Good crystals are rare. Found on Buffalo 

 Peaks ; Montgomery ; Head of Ohio Creek in volcanic breccia ; on 

 the Gunnison in tracliytes. 



Analcite. — In minute crystals in basalt, near Uucompahgre Peak. 



Andesite. — Minute crystals in the trachytes near Black Mountain. 



AnGtLESITE — Freeland Mine, on Trail Creek, In crystals at the Horse- 

 shoe lead mine, in South Park. Clifton lode, at Central City. Pros- 

 pector lode, in Arastra Gulch, near Silverton. 



Anhydrite. — On Elk Creek. Crystallized at the salt-works in South 

 Park. 



Anthophylltte. — North Boulder Creek. 



Anthracite. — Anthracite Creek ; "O Be Joyful" Creek; in the Elk 

 Mountains ; in Uucompahgre Canon. This anthracitic coal is of 

 Lower and Upper Cretaceous age. Partly its greater age, partly 

 other causes, have given to it the anthracitic character. Nearly all of 

 it was originally simply bituminous coal. Dr. Peale, with reference 

 thereto, says:* "The eruption of the trachyte found hear the coal 

 first mentioned, probably so heated it as to deprive it of the bitu- 

 minous matter." An analysis made by Dr. Peale of coal from An- 

 thracite Creek furnished the following result : 



Water 1.60 



Fisedcarbon 88.20 



Volatile combustible matter 3. 40 



Ash 6.80 



An average taken from seven analyses of Elk Mountain anthracite 

 furnishes : 



Water 2.757 



Fixed carbon 77.360 



Volatile combustible matter 13.620 



Ash 6.291 



Specific gravity 1. 740 



Antimony. — Gold Hill ; found there in minute crystals. 



Antrimolite. — See Mesolite. 



Apatite. — At Fairplay. 



Apophyllite. — Hunt's Peak. Eeported from some of the basalts near 

 San Luis Valley. 



Aragonite. — Occurring in the form usually termed flos ferric very 

 beautifully in Marshal's Tunnel, Georgetown, Golden. Table Moun- 

 tain. In the trachytes near Del Norte; on the Rio Grande, above 

 Fir Creek ; at Idaho Springs. 



* Rep. U. S. Geol. Surv., 1874, p. 176. 



