238 E. HA WORTH — THE OZARK UPLIFT AND ORE DEPOSITS 



quartz having yet been found at Galena, Joplin, or Webb city. In the 

 vicinity of Wentworth it is more abundant. In the southeastern district 

 quartz is abundantly found in connection with residual masses which 

 constitute the hills and adjacent granite and porphyry areas. 



GANGUE MATERIALS 



In the Galena-Joplin district about the only gangue associated with 

 the ores that occur in flint rock is a variety of silicious material pro- 

 duced in great abundance filling to different degrees the openings in the 

 rocks and generally carrying more or less galena and blende. This is 

 the cherokite of Jenny, and is variously composed of clay sediments 

 and silicious matter deposited from water solution, sometimes appear- 

 ing as an incoherent, soft, almost pulverulent mass, but frequently as a 

 hard, fine cement holding together the chert fragments, producing a solid 

 breccia. Between these two extremes are all possible variations. 



Calcite is found in large quantities in mines close to limestones, and 

 dolomite likewise is most abundant in such places. Barite is only 

 occasionally found about Galena and Joplin — so rarely, in fact, that the 

 miners have not yet learned to recognize it. Pj^rite and marcasite occur 

 in relative abundance ; but, compared with the volume of galena and 

 blende, they should be considered as of little importance. Barite grad- 

 ually increases eastward to the vicinity of Washington and Saint Fran- 

 cois counties, where it becomes sufficiently abundant to constitute an 

 important commercial product. 



PECULIAR ABSENCE OF IMPORTANT MINERALS 



It is quite important to note the universal absence from the whole 

 area of certain silicate and allied minerals, with the exception of those 

 found in the fissure veins cutting the crystalline rocks of the southeast. 

 The absence of quartz and feldspar and mica and garnet and topaz 

 and fluorite and wolframite and other minerals so frequently found as 

 gangue materials in mining districts where volcanic action, fumerole 

 action, or precipitation from hot solutions have produced the ore de- 

 posits, so characterizes the area that its significance becomes veiy impor- 

 tant. It corresponds entirely with the absence of volcanic materials 

 throughout the Ozark area, as already explained. It signifies that met- 

 amorphism of all kinds, other than weathering metamorphism, has had 

 no influence. It implies that the earth movements were entirely unac- 

 companied by heat phenomena of a volcanic nature, and that the move- 

 ments were so mild regional metamorphism from heat or pressure could 

 not be produced. It further has a strong bearing on the important 



