MERRILL AND TASSIN] THE CANYON DIABLO METEORITES 213 



A small amount of olivine was noticed as occurring in rounded 

 grains of a pale greenish-yellow color having the following composi- 

 tion: 



Si0 2 41.51 



MgO 52.70 



FeO 5.89 



NiO 0.29 



B. The Iron Shale 



That the oxidized portions of the shale balls (pi. xviii, fig. 2) and 

 the pear-shaped schistose masses of iron oxide shown in fig. 48 are 

 the result of weathering subsequent to the fall of the mass, as stated 

 by Derby 1 and Farrington, 2 does not seem to me to be open to ques- 

 tion when their field occurrence is known. That both have the same 

 origin is to me demonstrated by the following analyses : 



CuO, SO :{ and P.,0 5 absent. 



Analysis "A" was made by Mr. H. W. Nichols, 3 "B" and "C" were 

 made by me ; "B" on one of the inner layers of a shale ball having 

 an iron center ; "C" on a shale ball similar to that shown in fig. 49. 



These analyses, which while in the aggregate are alike, differ in 

 certain particulars to which attention should be called. Thus, Nich- 

 ols finds 3.91 per cent of FeO; I find but 0.65 per cent in that made 



'Am. Jour. Sci., 1895. 3d series, vol. 49, p. 101. 

 ~ Am. Jour. Sci., 1906, 4th series, vol. 22, p. 309. 

 r: Am. Jour. Sci., 1906, 4th series, vol. 22, p. 306. 



