PEALE.] CHEMISTRY OF DEPOSITS — GEYSERITES. 409 



Omitting the sesquioxides the proportion of the silica will be about 

 91 per cent., thus showing the specimen to be a geyserite. 



Gibhon Geyser Basin. 



Three specimens of geyserite from this basin were analyzed, and they 

 are probably the first analyses ever made of specimens from this locality. 



Sj)ecimenfrom Ecliimis Geyser. — The deposit from the water of Echinus 

 Geyser occurs as a thin coating on the rocks surrounding its basin. It 

 is usually lead-color or reddish. 



ANALYSIS. 



(Color, red; fracture, uneven; hardness, 5.) 



Per cent. 



Silica 73. 



Water 11.0 



Iron and aluminum sesquioxides 13. 5 



97.5 



Omitting the sesquioxides the relation of the silica and water will be — 



Silica 87.0 



Water 13.0 



showing the specimen to be a somewhat impure geyserite. Iron is a 

 prominent constituent in this specimen, and yet in the water no iron 

 was detected. (See analysis, page 391). The water is acid, and the iron 

 may be due to its action upon the surrounding rocks. 



Pearl Geyser. — The deposit surrounding this geyser is greenish-gray, 

 yellowish-white, and pearly. The specimen analysed has laminated 

 layer at the base, yellowish and resinous in appearance; above this it is 

 greenish-gray, with an irregular hard white surface, something like coral. 



ANALYSIS. 



(Fracture, irregular; hardness, 6.) 



Per cent 



Silica 87.1 



Water 10.6 



Aliimiua ) 



Linje > undetermined. 



Iron oxide > 



97.7+ 



The specimen contains a trace of sulphides which blacken a silver 

 dish when the finely powdered mineral is heated in it to 212 F.o 

 Hydrogen sulphide is evolved in small amount when the mineral is 

 heated with acid. 



Spring No. 25. — "White specimen 5 laminated in structure; fracture 

 uneven ; hardness, 5. 



ANALYSIS. 



Per cent. 



Silica 90.1 



Water 8.0 



Iron and aluminum oxides traces. 



98.1 

 Shoshone Geyser Basin. 



Only one specimen from this Basin was subjected to analysis, but 

 it came from one of the most interesting springs — the Bronze Geyser 

 or spring. It is surrounded by nodular masses which have a bronze- 

 colored surface, the metallic appearance of which is striking. It is re- 



