THE BARITE DEPOSITS OF MISSOURI 69 



The sections given above show the mode of occurrence of 

 the barite as it was seen in thousands of holes in the district. 



Water is found in some of the diggings. In generally owes 

 its presence to the gravel layers in the clay, or else it is found 

 just above the dolomite. 



There is a tendency for the barite to follow what the miners 

 have very appropriately called "leads." A good lead of barite is 

 conscientiously followed by them. These leads are apparently 

 residuals from solution cavities or veins. That they might be 

 from the former appears likely since they do not go downward 

 except at intervals. However, the fact that the material in the 

 lead may have been concentrated from a vertical dimension of 

 many feet makes it appear just as probable that a vein furnished 

 the barite. A drift three feet square usually includes all the 

 workable barite. 



Relationship to the other types. — Due to its great insolubility 

 the barite in the residual clays has accumulated with them as the 

 dolomite was dissolved and carried away by the ground waters. 

 The barite is in the dolomite in veins, disseminated masses, and 

 cave deposits. During weathering the dolomite has been re- 

 moved from the barite in all these different kinds of deposits, 

 allowing the barite to accumulate along with the clay. The resi- 

 dual barite has a very intimate relationship with the other types 

 of deposits as it is dependent upon them. 



Geological distribution. — There is a remarkable persistence 

 in the geological distribution of the residual barite deposits. In 

 the Washington County district the barite is found only in the 

 Potosi and the Proctor formations, and of these two formations 

 the Potosi contains by far the greater part. The contact of these 

 two formations passes through or adjacent to the best deposits. 

 Further, the upper part of the Potosi formation contains these 

 deposits more abundantly than the lower portions, altho the de- 

 posits at Fletcher are well down in the formation. This feature 

 is apparently due to the faulting and erosion already suggested 

 as occurring in the Potosi. 



In the Central district the most important deposits are in the 

 Gasconade, but the Roubidoux and Jefferson City formations 

 also contain some barite. In all cases most of the barite comes 

 from the residual clay over the formations. 



