Plate 57 



1. Pine River, Wisconsin; an undescribed iron that may be provisionally classified as an 

 atypical coarsest octahedrite with accessor}- silicates. An example of a solid solution of 

 phosphorus in nickel-iron; in artificial irons such a homogeneous solid solution should not 

 contain more than about 1.7 percent of phosphorus. With ordinary etching the entire field 

 appears to be kamacite, with dark areas of silicate and oxide. Light picral; X 60. 



2. Pine River. The area shown in figure 1 with additional etching 5 minutes with 

 neutral sodium picrate. The area at the right is shown to contain phosphorus, evidently 

 in small proportion as it darkens only slighth- and the reticulated pattern of the stain is 

 coarse and faint. Grain boundaries within the phosphorus area appear more distinctly. 



3. Pine Ru'er. An example of a coarse reticulated pattern in the pellicle of picrate 

 stain. Light picral and 5 minutes neutral sodium picrate; X L^O. 



4. Pine River. Part of the area shown in figure 3, X 600. Portions of grain boundaries 

 are apparently darkened b\- h\'droxide. 



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