Plate 19 



1. GuFFEY, Colorado; nickel-rich ataxite; Ni-Co 11.09 percent. The nickel content of 

 Guffey is less than that of a number of finest octahedrites, and little more than that of 

 Bacubirito and Ballinoo. Its structure, however, resembles that of the higher-nickel atax- 

 ites, though coarser. The photograph shows the prevailing structure at moderate magnifi- 

 cation. Picral 45 seconds; X 60. American Museum of Natural History. 



2. Guffey. General structure at higher magnification. The white areas are kamacite. 

 Taenite is darkened because of supersaturation with respect to kamacite. Picral 25 seconds; 

 X 600. 



3. Wiley, Colorado; nickel-rich ataxite; Ni-Co 12.31 percent. This iron is in the transi- 

 tional class, but the author would assign it to ataxites. The kamacite body at left contains 

 an inclusion of iron-phosphide eutectic. Picral 40 seconds; X 60. 



4. Wiley. An example of the occasiona' areas of densely crowded kamacite spindles, 

 the interstices filled with fine to dense plessite. Picral 40 seconds; X 60. 



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