THE BARITE DEPOSITS OF MISSOURI 95 



Many saline springs deposit barite after their waters have 

 mingled with sulfate waters. Examples of such springs are those 

 at Clausthal, Germany, and the brines in the colliery at Notting- 

 ham, England, described by Clowes.^ 



The features cited by Lindgren as characteristic of shallow 

 veins are (1) the filling of open fissure, (2) crustification, and 

 (3) splitting and chambering in short irregular veins. Deposi- 

 tion below impervious beds is often noted. Gold and silver de- 

 posits are most common, but large deposits of lead and zinc are 

 known. Base metal minerals are pyrite, occasionally marcasite, 

 chalcopyrite, and rarely alabandite and arsenopyrite. Quartz is 

 especially common, often as chalcedonic varieties; calcite, dolo- 

 mite, barite, and fluorite are locally the abundant gangue miner- 

 als, while siderite is rare. 



Recalling the descriptions of the Missouri barite deposits, it 

 will be seen that they are remarkably similar to these veins, in 

 structure, shape, and mineralogy. The greatest difference is 

 that there are no visibly associated igneous rocks. This, how- 

 ever, cannot be taken as proof that none exist below. The dike 

 in the Central district proves that there has been movement 

 among the underlying igneous rocks in geological times later than 

 the deposition of the rocks enclosing the ore bodies. Other dikes 

 later than the Cambrian rocks are known to occur in southeast- 

 ern Missouri. That the Missouri ore deposits might be geneti- 

 cally connected with igneous rocks, tho the latter are not visible, 

 had been the writer's opinion ever since he began to study them 

 in detail, and he was glad to see Professor Pirsson's suggestive 

 communication in Economic Geology,^ since it indicated that 

 others had the view that igneous activity does not need to mani- 

 fest itself at the surface as dikes and lava flows to prove its pres- 

 ence. 



It is interesting to note that some German investigators look 

 upon the Missouri lead and zinc deposits as genetically connected 

 with igneous rocks. Beck^ says : 



'Clowes, F., "Brines from Colliery, Nottingham, England," Proc. 

 Roy. Soc, vol. 46, p. 338. 1889. 



"Pirsson, L. V., Econ. Geo!., vol. 10, pp. 180-186. 1915. 

 *Beck, R., "Nature of Ore Deposits," p. 550. 



