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S. W. McCALLIE 



ends. In a tranvserse section they are ellipsoidal, with sharp, knife- 

 like edges. Their sides are often striated, and occasionally indented 

 by depressions, or in some cases even pierced by the feldspar 

 pebbles (see Fig. 2). The color, when unstained by foreign material, 

 is that of milky quartz. The texture is granular, and the larger 

 pebbles are slightly elastic. The latter property seems to be most 



P'iG. 3. — Micro-photograph of transverse section of stretched quartz pebble. 



pronounced when the pebbles are first taken from the bed. After 

 drying they become somewhat brittle and have to be handled with 

 more care. The individual pebbles appear to have no cleavage, 

 but break as readily in one direction as another. The following 

 analysis by Doctor Edgar Everhart shows that they are almost pure 

 silica : 



Soluble silica 1.29 



Insoluble silica 97-84 



Total silica (SiOa) 99-13 



Ferric oxidee (Fe^03) 0.77 



Alumina (AI2O3) 016 



Total 100.06 



