THE BARITE DEPOSITS OF MISSOURI 85 



pyrite, the oxidation of the latter did not furnish the sulfate radi- 

 cal. As a great many veins and most of the disseminated barite 

 are not associated with any sulfide whatever, some other source 

 for the sulfate must be sought. 



The ordinary carbonate water contains a small amount of 

 the sulfate radical, a part of which may be derived from decay- 

 ing organic material at the surface (all organisms contain some 

 sulfur) and a part from the breaking down of sulfides in the 

 rocks. Such minerals are almost always present, but generally 

 in very small amounts. Their alteration means the production of 

 sulfates and possibly of hydrogen sulfide. 



This sulfate radical would, if barium were present in the so- 

 lution, unite with it because of the low solubility of barium sul- 

 fate. This would permanently remove the sulfate radical from 

 solution, and prevent any further participation in the reactions in 

 that vicinity. 



Certainly the amount of sulfate likely to be present in these 

 solutions is sufficient to form barium sulfate from all the barium 

 in the carbonate rocks. But, as has been pointed out, there is not 

 sufficient barium in the rocks to form the large deposits of the 

 district, and likewise the amount of sulfides in the rocks is 

 probably insufficient to produce anywhere near the amount nec- 

 essary to furnish the sulfide radical which has gone to form the 

 sulfides occurring in the veins. 



Conclusions concerning the barite 



The Missouri barite deposits are believed not to have been 

 formed by concentration from surrounding rocks, for the follow- 

 ing reasons : ( 1 ) carbonate rocks, the dominant type in this 

 area, have been shown to contain no barium, save in rare in- 

 stances where it is not certain that it was not actually introduced 

 into the rocks by later solutions; (2) the waters in such rocks 

 are dominantly carbonate waters which are poor solvents for 

 barium salts; and (3) the rocks of the region are of very low 

 permeability, save along the divisional planes where the activity 

 of solutions is confined to the immediate walls. 



