72 



FiKLD Columbian Museum — Geology, Vol. III. 



II. OCTAHEDRITES. 



'I'he meteorites of this class are the most abundant among iron 

 meteorites. According to the width of the lamellae as seen in etched 

 sections, they are divided as follows: Coarsest octahedrites, lamellae, 

 manv mm. to 2.5 mm. in width; coarse octahedrites, lamelh^ 2-1.5 

 mm. in width; medium octahedrites, lamellce 1.0-0.5 mm. in width; 

 fine octahedrites, lamelLie 0.4-0.2 mm. in width; finest octahedrites, 

 lamella; from 0.2 mm. down. While no sharp line of separation can 

 be drawn between these groups, the members of each group present as 

 a rule characters more or less peculiar to themselves. As compared 

 with the hexahedrites, the octahedrites differ in structure in being 

 made up of lamellae arranged in accordance with the planes of the 

 octahedron. These lamellae in turn are composed of two or more 

 alloys of nickel-iron. In composition a higher percentage of nickel- 

 cobalt may be noted among the octahedrites, as compared with the 

 hexahedrites, and schreibersite and troilite are far more abundant 

 than in the hexahedrites, Cohenite, which is not known to occur in 

 the hexahedrites, is characteristic of certain groups of the octahe- 



COARSEST, 



Name. 



Fe. Ni. 



Arispe 



Canvon Diablo. , 



92.27 ,7.04 

 95 -370 3 -945 

 91.3967-94 



Canton • 91 .96 



Central Missouri... 94-73 

 Nelson County .... 93. 10 



Pittsburi^- '92.81 



" 93-38 



Ponca Creek 



Sao Julifio. 

 Seelasjren. 



91-74 

 91.74 



89-39 

 90.00 



92-33 



6.70 

 4.62 

 6.11 

 4.66 



5.89 



6-53 

 7.08 



Co. 



.50 

 .18 

 ■41 

 •39 

 1.24 



8.27 



5-31 

 6.23 



-43 



.67 



Cu. 



03 



Cr. 



.144 



.179 

 . II 



• 44 



.05 



•25 

 •15 

 .01 

 .01 

 .26 



tr 



.004 

 .01 

 .02 



.04 



.07 



.417 



•52 



tr 



.047 

 tr. 



1. 16 

 .02 



CI. 



In- 



.26 



Miscellaneous. J , 



Mn 14 



Chromite. .07 



Sn 06! 



Sn 06 



Mn 91 



Cu. +Sn.. .o;| 



