MINES OF CARTERVILLE, JASPER CO., MO. 71 



form of cubes. It is more abundant in the broken chert beds. Beautiful octag- 

 onal crystals occur and we find them arranged in handsome clusters. 



Zind blend (sphalerite) is chiefly abundant in the chert beds, acting as a 

 cement to the broken fragments of chert, the whole appearing as a coarse breccia. 

 The dark chert often contains disseminated blende; the white does not, but blende 

 is often seen crystallized on the chert. 



The general position of the strata in the mines is an approach to horizon- 

 tality, but they undulate very much in the mines. In sinking the shafts the chert 

 beds (No. 5,) are reached at eighty feet or more below the surface. They are 

 much broken and sometimes do not seem to be at all stratified. 



The lower chert beds (No. 5,) or mineral-bearing rocks, are of a white, 

 gray, or dark blue. The ore is rarely contained in the chert itself, but is chiefly 

 confined to the surface of the rock, but the darker colored rock sometimes is por- 

 ous and includes mineral ores, apparently a replacement of the dissolved rock. 



The clay bars, or bands, or pockets, rarely contain valuable minerals, but 

 often contain a good deal of iron pyrites either in crystallized forms or else thor- 

 oughly impregnating the shale so as to darken it. 



The darker chert is sometimes colored by the zinc ore. It also passes into a 

 densely crystalline quartzite. 



The ores are also sometimes found occupying drusy cavities which are some- 

 times beautifully studded with minerals. In them we sometimes find zinc blende, 

 sometimes calcite, sometimes dolomite. 



In the North Carterville mines a dark banded quartzite was observed, show- 

 ing obscure deposits of zinc ore at the junction of bands and also disseminated 

 ore. 



At one place in the mines, the lowest seen rock was a dark banded quartzite, 

 and a breccia of calcite, chert, and blende, with a deposite of galena just above. 

 At another place found bituminous limestone. The quartzite sometimes presents 

 a bony structure and incloses blende. Blende also occurs in cavities with pyrites 

 crystallized upon it. Dolomite was found occupying spaces between the blende 

 crystals. The granular blende is apparently of older age than the crystallized. 

 The galena generally seems to be older than the blende, but sometimes they are 

 of equivalent age. The pyrites is younger or newer than either. Their order of 

 formation is about as follows : 

 I. — I. Galena, blende. 



2. Galena, pyrite. 



3. Galena, dolomite. 

 II. — I. Blende, pyrite. 



2. Blende, dolomite. 



3. Granular blende, crystallized blende, or condensed thus : 

 Galena, 



Granular blende. 

 Crystallized blende. 



Dolomite, Pyrite, Calcite. 



