THE BARITE DEPOSITS OF MISSOURI 81 



Method of concentration 



Practically all geologists dealing with the subject assume 

 that ground water is the transporting agent for the barium. The 

 ability of ground waters to transport barium depends upon their 

 solvent power for the barium salts in the rocks, and their ability 

 to find a passage thru the rocks in order to reach the barium. 



Solubility of barium salts. — Barium sulfate is the most in- 

 soluble salt of barium known to occur in the rocks. Its solubility 

 is generally stated as 1 in 400,000 parts of water. Certainly this 

 solubility is increased by the presence, of alkaline bicarbonate and 

 by carbon dioxide in the water, but how much is unknown. That 

 it is not a very important increase is shown by the lack of evi- 

 dence of solvent effects upon the barite found in the surface 

 rocks, where such solutions are probably most abundant and ef- 

 fective. P. Carlos^ proved that alkaline carbonates with an ex- 

 cess of CO2 could hold barium in solution in the presence of sul- 

 fates. The waters in most carbonate rocks are of this type, but 

 whether they are of sufficient strength to attack and remove the 

 barite is to be doubted for reasons given later. Some men have 

 reported having found barite which showed signs of leaching, 

 but these cases might have been the very irregular surfaces pro- 

 duced by the removal of minerals and rocks to which the barite 

 was formerly attached. It was found that these irregularly pit- 

 ted surfaces on the Missouri barite represented casts of minerals, 

 and in one case casts of pieces of rocks. 



Some men have suggested that barium exists in the various 

 rocks as the carbonate. If this is the case it should be found fre- 

 quently in limestones and dolomites, and this is not true. Clowes* 

 states that a sandstone (Keuper in age) at Beeson Hill, Notting- 

 ham, England, contains BaCOg. This is the only instance where 

 the barium salt in a rock was actually found to be the carbonate. 

 It is rather strange that it does not occur more commonly as its 

 solubility also is very low; 100 grams of water at 18° C. dissolve 

 .0023 grams of barium carbonate. The reason for this common 

 occurrence of the sulfate, rather than the carbonate, lies in the 



^P. Carlos, Jour. Chem. Soc. Abst., vol. 80, Pt. 2, p. 506. 1901. 

 ^Clowes, F., Brit. Assoc. Adv. Sci., p. 594. 1889. 



