NOTE ON AN OCCURRENCE OF BLENDE IN 



LIGNITE. 



H. A. WHEP^LER, E. M. 



(Read at the meeting of Academy of Science, of November 19, 1894.) 



In exoavatiDsr for the foundations of the new high-service 

 pumping-station at Baden, in North St. Louis, fragments of 

 blende-bearing lignite were found in the " Ferrusinous Sand- 

 stone" at a depth of about 25 feet. The pit is in the river- 

 bottom at the base of the bluffs that mark the western edge 

 of the valley of the Mississippi river, being about half a mile 

 west of the present river-bank, and furnishes the following 

 section : — 



Black "Gumbo" Soil 2' to 3'] Recent. 



Fine Sand 12' to 18' t, (Mississippi River) 



Coarse Sand and Pebbles 2' to 8' J Deposits. 



Grav to Drab Sandstone 2' to 10' "1 „ ^ r-, -, ^, 



Yellow Shale 1 to 2^ -^ 



Green Shale - 2' to 3' J ^''"^*' 



St. Louis Limestone — average depth, 32' y Sub- Carboniferous. 



The excavation stopped at the limestone, on which the coal- 

 measures rested unconformably. 



The sandstone in which the fra2;ments of lignite occurred 

 was coarse-grained, porous, cross-bedded, light-gray to dark- 

 drab in color, and rich in lignitic streaks with occasional 

 fragments several inches in thickness. Some of these frag- 

 ments of lignite or brown-coal are full of longitudinal and 

 transverse desiccation cracks, which are completely filled with 

 a crystalline mixture of sphalerite or zinc-blende, calcite and 

 pyrite. The blende decidedly predominates, forming thin 

 seams -jV to ^ inch in thickness through the lignite, and 

 is light to dark brown in color, has a perfect cleavage, and the 

 usual resinous fracture. Calcite, of the white, crystalline 



(123) 



