TITLES AND ABSTRACTS OF PAPERS 79 



This seems to be a new occurrence for barite. It has been reported as 

 occurring in veins, as filling in the interstices of brecciated limestone, quart- 

 zite, sandstone, and chert, as nodules and irregular masses in residual clay, 

 in geodes associated with drusy quartz, and always described as crystalline. 

 J. P. Rowe" describes a deposit of nodular barite and selenite from Montana 

 in which the barite is nodular, radiated, and fibrous. The shape of the nodules 

 is spheroidal and the size of the bodies varies from 5 to 10 centimeters in 

 diameter and 3 to 7 centimeters in thickness. The mineral is whitish blue in 

 color and has a specific gratify of 4.7. 



The Saratoga barite somewhat resembles that from Montana in color and 

 form, but it is distinctly oolitic or pisolitic, and it is partly cryptocrystalline 

 to amorphous. 



Chemical Composition and Origin of the Concretions 



As stated above, the flame test indicated barium, strontium, and a trace of 

 potassium. A chemical analysis made by Mr. L. J. Youngs, of the Department 

 of Geology and Mineralogy of the Pennsylvania State College, to whom I am 

 indebted for these figures, showed the following percentages : 



Si02 0.98 SO3 35.104 



Al,03 0.41 H,0 , ^ g^ 



!»■ 



FeaOg 0.07 Vol. matter 



CaO 2.129 BaS04 88.54 



SrO 2.067 SrS04 3.76 



BaO 58.17 CaS04 5.17 



From this analysis it is seen that the oolites consist chiefly of barite, with 

 small amounts of gypsum and celestite. , Since they are associated with warm 

 water and oil, and since the sandstones are mammilla'ted on the lower side, 

 it seems probable that the barium was carried upward in solution and pre- 

 cipitated by coming in contact with the sulphuric acid waters, which are 

 associated with the oil. The barium may have been carried as a bicarbonate 

 or in a dilute solution of a carbonated alkali. Bischof states that barite is 

 practically decomposed by a dilute solution of a carbonated alkali at a tem- 

 perature of 77° to 82° Fahrenheit, and at 212° only 1,000 parts of water are 

 required to dissolve barium silicate. W. P. Headden describes the Doughty 

 Springs of Colorado, in which Na, CI, and CO2 are abundant, the latter both 

 as free gas and as bicarbonates, and in which barite sinter is being deposited 

 in large quantity .^^ Whether the barium in Texas be carried as a bicarbonate 

 of barium, as barium sulphate dissolved in a carbonated alkali, or as a barium 

 silicate, it would readily be thrown down by the sulphuric acid present, as the 

 acid would set free alkali sulphates, which might remain in solution, and 

 precipitate the barium as sulphate. 



Eead in full from manuscript. 

 The section adjourned. 



2» American Geologist, vol. 33, 1904, pp. 198-199. 

 38 Am. Jour. Scl., 4th ser., vol. 19, pp. 297-309. 



