Plate 23 



1. KoKOMO, Indiana; nickel-rich ataxite; Ni-Co 16.83 percent. General structure, 

 with two of the occasional minute kamacite bodies. Picral 45 seconds; X 60. American 

 Museum of Natural History. 



2. KoKOMO. An area similar to figure 1. The paraeutectoid structure is irregular. 

 The taenite border of the kamacite body merges in places with the corresponding compo- 

 nent of the groundmass. In places the taenite shows complete equilibrium; in others a 

 grayness indicates supersaturation with respect to kamacite. Picral 25 seconds; X 600. 



3. Tlacotepec, Mexico; nickel-rich ataxite; Ni-Co 16.91 percent. General structure, 

 with two kamacite spindles. Picral 50 seconds; X 60. 



4. Tlacotepec. An area similar to figure 3 at high magnification. The kamacite 

 spindle is seen to be surrounded by an irregular border of taenite, all in a groundmass of 

 paraeutectoid structure in which some of the taenite particles are darkened by reason of 

 supersaturation. In a few places the clear taenite of the border can be seen to merge with 

 the same component of the paraeutectoid, but generally the merger is obscured by the 

 irregular border of black gamma-alpha mixture that surrounds the spindle. Picral 25 

 seconds; X 600. 



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