AEi. 13 MINERALS FROM SOUTHERN UTAH SHANNON 6 



The Utah mineral is so similar in appearance and associations to 

 that from Wyoming that, were specimens from the two localities 

 mixed it would be impossible to separate them. Like those described 

 by Erickson the Utah specimens consist of fibrous veins up to 1 

 centimeter thick, of glassy transparent tschermigite cementing frag- 

 ments of lignitic shale and nodules of yellow jarositic material. 

 People familiar with the Wj'oming specimens insisted that the Utah 

 material must be from the same locality but, aside from the other 

 evidence, this is disproven by the upper Cretaceous fossils in the Utah 

 specimens. The Wyoming mineral occurs in the Wasatch formation 

 of lower Eocene age and the tschermigite-bearing bed is immediately 

 below the upper Eocene Green River shale. 



The veinlets of Utah tschermigite seldom exceed 1 centimeter in 

 thickness, and most of them are much thinner than this in the 

 specimens at hand. The mineral is transparent, colorless, and glassy, 

 with only an indistinctly fibrous structure or appearance, which is 

 mostly due to canals or elongated cavities in one direction across the 

 veins. Ample material was available for analysis. After washing 

 with ak-ohol and drying in air a 2.5-gram sample was weighed out, 

 dissolved in water, and filtered. The insoluble material was chiefly 

 lignite, which was weighed after air-drying for several days. The 

 solution, made up to definite volume, was divided into aliquot por- 

 tions, each equivalent to one-half gram of sample. All constituents 

 except water were determined on these portions. Ammonia was 

 determined by the addition of an excess of potassium hydroxide and 

 distilling the liberated ammonia into a measured volume of stand- 

 ard acid, the excess of acid being titrated with standard alkali in 

 the usual manner. The other constituents were determined by the 

 customary methods. The analysis gave the following results : 



Analysis of tschermigite from Utah 



(Earl V. Shannon, analysts 



Per cent 



Insoluble (lignite, etc.) 0.04 



AI2O3 11. 86 



FejOa Trace. 



CaO . 10 



MsO .28 



NajO . 48 



K.0 . 25 



(NH4)20 4.78 



CI .04 



SO3 35.78 



H.0 above 110° C 21. G8 



HO below 110° C 25.16 



100.45 



