95 UNIVERSITY OF MISSOURI STUDIES 



"The presence of barytes and fluorite, in fact the entire min- 

 eral assemblage of the deposits, so closely resembling that of the 

 genuine silver-lead veins of hydrothermal origin, indicates that 

 the hydrothermal theory is the correct one, especially since it will 

 hardly be proved that the zinc and lead contents of the limestone 

 were not themselves introduced by subsequent infiltration." 



Source of the barmm in rising solutions. — Clarke's average 

 analyses of the igneous rocks shows .092 per cent of barium. 

 When this is contrasted with the .00246 per cent, which is the 

 average in the dolomite of southeastern Missouri, it is found that 

 there is about 36 times as much barium available in the igneous 

 rocks as there is in an equivalent mass of sediments. Furthermore, 

 the high temperature and included solvents in the igneous solu- 

 tions, assuming that they are similar to those found to have ex- 

 isted in other deposits, would greatly facilitate the gathering to- 

 gether of the barium in the igneous rocks before their consolida- 

 tion. Likewise, the fact that barium rarely exists as a simple 

 pyrogenetic silicate would seem to favor the belief that it is con- 

 centrated into the magmatic solutions, to be carried upward with 

 them when they are freed from the rock. Nearer the surface its 

 great stability as a sulfate enables it to exist under a wide range 

 of conditions, even at the surface. 



The writer believes that the barite veins of Missouri were 

 deposited by waters derived from igneous rocks. 



Barite deposits of the United States. — As stated at the be- 

 ginning of the discussion of the origin of barite, the commonly 

 expressed opinion is that the barite in the Appalachian and the 

 Missouri areas owes its origin to cencentration from the sur- 

 rounding rocks. The writer wishes to present a short account of 

 these various deposits with a statement of their mode of occur- 

 rence and a designation of the associated rocks, because there is 

 an interesting similarity in them, aside from the fact that all show 

 about the same type of residual concentration. 



There are several important barite deposits in the United 

 States. The states rank as follows in the importance of their 

 production: Missouri, Tennessee, Georgia, North Carolina, Vir- 

 ginia, South Carolina, Alabama, and Kentucky. In general it 

 may be said that most of the production comes from residual de- 

 posits, which were formed by the weathering of veins and re- 



