THE BARITE DEPOSITS OF MISSOURI 79 



tenden County, Kentucky. He reports the analyses of three 

 other Umestones in which no barium was found. Watson^ gives 

 the following analyses of limestones from Campbell and Pittsyl- 

 vania Counties, Virginia: 



I II III 



BaSO^ .62% .65% 1.62% 



I. Crystalline limestone from Hewitt mine, Campbell County. 

 II. Crystalline limestone from Hewitt mine, Campbell County. 

 III. Limestone from Ramsay mine, Pittsylvania County. 

 It is evident that the barium sulfate in the above rocks was intro- 

 duced into them from the outside, because such amounts of 

 barium sulfate are not found, even in igneous rocks. This con- 

 clusion is strengthened by the fact that the samples were taken 

 from barite mines. The presence of metallic sulfides near a vein 

 or ore body would be interpreted by most geologists as due to re- 

 placement by the mineralizing solutions. The writer believes this 

 applies here. Watson reports a trace of BaO in a black clay 

 from which some of the barite is mined. Most of the barite in 

 this locality occurs as lenses in limestone which is interbedded 

 with the black clay and some chists of various sorts. 



Dickson* found only traces of barium in the dense limestone 

 adjacent to a barite vein at Kingston, Ontario. In the weathered 

 portion of the limestone and in the soil, which is in part glacial, 

 he obtained from .03% to .09% of BaO. Igneous boulders on 

 the surface gave from .11% to .30% BaO, a marked difference 

 from the amount in the limestone. 



These figures show that limestones at the best contain but 

 a small amount of barium and that the vast majority of them do 

 not show any at all. Lindgren^ suggests that, when limestones 

 are more carefully analyzed, barium as well as other minor acces- 

 sory constituents will be found. This appears doubtful because 

 the result of recent analyses fail to show any barium, and at 

 present the chemical analysis of limestones and dolomites is veiy 

 accurately done. 



The other two common sedimentary rocks, shale and sand- 

 stone, show considerable amounts of barium, but these rocks are 



'Watson, T. L, Min. Res. of Va., pp. 316-317. 1907. 



^Dickson, C. W., ibid. 



'Lindgren, Mineral Deposits, p. 230. 



