76 GEOLOGY— RESULTS OF CHEMICAL ANALYSES. 



COMPOSITION. 



Si. 74.758, Al. 4.517, Fe. 9.152. 

 Ca. 1.469, H. 10.146 = 100.042. 



E. Specific gravity, 2.2431 ; structure, granular ; color, gray ; differs from B only in possessing 

 a somewhat finer granular structure, and is slightly tinged red by a larger quantity of sesqui" 

 oxide of iron. 



COMPOSITION. 



Si. 81.554, Al. 3.331, Fe. 8.076. 

 Ca. 1.443, H. 6.137 = 100.541. 



F. Specific gravity, 1.970 ; structure, finely granular ; very soft and friable ; full of irregular 

 seams or cracks, along which it breaks readily ; color, grayish, with yellowish streaks. 



COMPOSITION. 



Si. 61.020, Al. 13.017, Fe. 8.639. 

 Ca. 1.257, H. 15.292 = 99.215. 



G-. Specific gravity, 2.000; resembles F in many particulars, and differs from it only in 

 having some small elliptical or spherical portions of half an inch in diameter, perfectly white, 

 while layers surrounding these have a darker shade of gray, thus presenting a motley appear- 

 ance ; and in containing no yellowish streaks, which exist in F, in consequence of containing a 

 larger proportion of sesquioxide of iron. 



COMPOSITION. 



Si. 75.746, AL 10.326, Fe. 6.016. 

 Ca. 1.773, H. 7.339 = 101.2. 



H. Specific gravity, 2.2705; granular structure; color, grayish; soft and friable; is a 

 deposit from the hot springs, which forms incrustations upon objects in the water. 



COMPOSITION. 



Si. 1.615, Ca,C. 40.623, Na,C. 45.567. 

 H. and organic matter, 10.623 = 98.398. 



The next four, marked b, c, d, and e, have been changed by agency of water; differ from the 

 unchanged in possessing superior hardness and specific gravity without differing very much in 

 chemical composition. 



b. Specific gravity, 2.2774; coarsely granular structure ; compact; color, gray, with a reddish 

 tint ; a complete sandstone. 



COMPOSITION. 



Si. 81.592, Al. 4.144, Fe. 5.096. 

 Ca. 1.627, H. 6.578 = 99.037. 



