86 UNIVERSITY OF MISSOURI STUDIES 



The other minerals of the deposits 



The above discussion has been confined entirely to the barite 

 since it is necessary to account for the presence of that mineral. 

 But the theory which accounts for the concentration of the barite 

 must also account for the presence of the quartz, pyrite, mar- 

 casite, galena, and sphalerite as well as the minor amounts of 

 chalcopyrite in the deposits. To discuss each of these in detail 

 is impossible in this paper, but the application of the above prin- 

 ciples to these minerals in a group may be made. 



The source of the minerals. — The quartz could have come 

 from almost any of the formations in the region, save the Proc- 

 tor, as all but it are decidedly siliceous, that is, they contain a 

 great deal of chert The presence of the iron sulfides is not so 

 readily explained, but essentially all kinds of sediments contain 

 these sulfides in varying amounts. They are commonly primary 

 constituents of the rocks. Small quantities of lead, zinc, and cop- 

 per are present in the formations, as shown by Robertson's analy- 

 ses made at the same time that he determined the barium content 

 of the limestones and dolomites. 



The following are his averages: 



Percentage Percentage Percentage 

 of zinc of lead of copper 



Igneous 00901 .00397 .00590 



Cambro-Ordovician limestone and 



dolomite 00425 .0009 .00128 



Mississippian limestone in Mis- 

 souri 00104 .00115 .00202 



These figures are of about the same order as those for the 

 amount of barium present. With such minute amounts it would 

 appear difficult to concentrate them. The problem is less diffi- 

 cult in the Washington County district than in the Central dis- 

 trict, because in the former there is less galena and sphalerite in 

 the deposits and also because barite predominates in the veins. 



Transportation. — The chemistry of the transportation is 

 hypothetical, as can be seen by consulting the reports of Bain, 

 Smith, Siebenthal, and Buckley and Buehler on the Joplin dis- 

 trict; of Buckley on the southeastern Missouri deposits; and of 



