THE BARITE DEPOSITS OF MISSOURI 87 



Other writers on similar types of deposits. The common belief is 

 that the transportation of the metals is possible, and this method 

 is used in explaining the origin of the deposits. 



As to the adequacy of solvents it is commonly held that sili- 

 ca is transported in underground solutions by alkaline carbonates. 

 If such be the case, the character of the solutions in 

 these rocks is such as to favor the solution and transference of 

 silica. But the concentration of the quartz as a part of the resi- 

 dual material, even while in the process of concentration it is 

 constantly bathed in an alkaline carbonate solution, is strong evi- 

 dence against such a conclusion. 



The same question of the ability of the solutions to penetrate 

 the rocks when their circulation is so confined as to allow them 

 to act only upon the thin layer adjacent to the divisional planes, 

 is applicable here as it was in the case of the barium, and the con- 

 clusion must be the same: that it is improbable, if not impossible. 



Deposition. — A further bit of evidence against this mode of 

 deposition is suggested by the discussion of these other minerals. 

 They must be removed from the country rock and deposited in 

 veins or replace the dolomite always in the same order. A care- 

 ful study of the district gave only the following order: (1) 

 quartz, (2) pyrite or marcasite; (3) galena and sphalerite, (4) 

 barite. It is improbable that solutions would always dissolve the 

 same mineral at the same time and have it ready to deposit in the 

 vein when the preceding mineral had been deposited. There is 

 no overlapping of any of these minerals. The galena and sphal- 

 erite are simultaneous, but otherwise there is an interval of time 

 between the minerals. 



When the factors in the concentration of the barite are con- 

 sidered ii^ connection with the facts regarding the source, accu- 

 mulation, itnd order of deposition of the associated minerals, the 

 correctness of the theory that barite deposits have been derived 

 from the surrounding rocks appears to be rather unlikely. 



DEPOSITION BY RISING SOLUTIONS 



The view that the barite was deposited by rising solutions, 

 probably derived from igneous rocks below, may also be applied 

 to these deposits. Such solutions should be considered as being 



