222 GEOLOGICAL SURVEY OF THE TEREITOEIES. 



est) covered a space of perhaps 600 square feet, and emitted a vapor 

 which could be seen for a long distance. 



Surrounding it was a marsh or swamp in which salts from the evap- 

 oration were deposited. The temperature at the edges was perhaps 

 110° to 120° Fahrenheit, and bubbles of gas rise in many places to the 

 surface, and are caused bj^ the weight of a person walking around the 

 edges in the immediate vicinity of the soggy soil. Specimens of the 

 salts, as they lie loosely like an efflorescence, and also of the same ma- 

 terial in a harder form like California marble, (only not so variegated in 

 color,) were collected, but no opportunity oftered to examine them. 



The surrounding country, and our road towards Roman's Creek, is for 

 miles covered with a white deposit called by the natives " alkali," sim- 

 j)ly. It gives the landscape the appearance of being covered with snow. 

 This "alkali" is probably composed of nitrate of potash, sulphate of 

 lime, and perhaps other salts in smaller quantities, but has not been yet 

 a^nalyzed. The same deposit has been observed in the neighborhood 

 of St. Vrain's Creek, and in the basaltic region below Trinidad on our 

 route down to Santa Fe. 



Minerals ohscrved in Netv Mexico, 



MINERALS OF COMMERCIAL VALUE. 



Iron pyrites, copper pyrites. — Mostly auriferous. Widely distributed in veins over tlie 

 flaulis of the Rocky IMountains, in New Mexico, and in numerous lesser chains of 

 granitic and metamorphic rocks. 



Malachite, green vitriol, blue vitriol. — Principally from decomposition of the above, 

 wherever the ores have been exposed to weathering. Widely distributed in veins 

 over the flanks of the Rocky Mountains, in New Mexico, and in numerous lesser 

 chains of granitic and metamorphic rocks. 



Zincblende. — Often argentiferous. San Dia, &c. 



Galena. — Often argentiferous. Maxwell's, near More. 



Brittle silver. — Maxwell's, near Moro. 



Fahlerz. — Maxwell's, near Moro. 



Specular iron ore. — Real Dolores, near Ortiz mine. 



Red and brown hematite. — Widely distributed. Old Placer, &c. 



Magnetic ]>yrites. — ^New Placer. 



Coal. — Raton Mountains, Maxwell's, Real Dolores, &c. 



Cerussite. — Maxwell's. 



Anglesite. — Maxwell's. 



Native gold. — Arroyo Hondo, Morena, Brahm Lode, New Placer, &c. 



Native silver. — Maxwell's. 



Horn silver.— Maxwell's. 



Titanic iron ore.— Real Dolores. 



Smithsonite. — San Dia. 



Silver glance. — Morena, New and Old Placers. 



Light and dark ruby silver. — Maxwell's. 



Spathic and micaceous iron ores. — Real Dolores. 



Turquoise, (2AI2O3 . POs-fSHO.) — Cefillos, between Santa F^ and the San Lazaro 

 Mountains. 



CHARACTERISTIC BIINERALS. 



Quartz. — Forms gangue rock of most of the veins ; common. Agate, chalcedony, and 



silicified wood in the bed of the Galisteo. In the granites, gneisses, &c. 

 Hydrated oxide of iron. — Occurs with the coal beds, and colors the rocks near exposed 



veins, &c. 

 Opal. — Galisteo beds. 

 Feldspar. — Everywhere among the granitic rocks. Orthoclases predominant. Oligo- 



clases also abundant. Albite is found near Moro. 

 Labrador. — Basalt dikes, &c. 

 Hornblende. — Syenites, some basalts. 

 Potash and magnesian mica. — Gneisses and granites, and in the greissen found near 



Moro. 

 Leucite. — Trachytic lavas near Fort Union. 



