Plate 55 



1. Cedartown, Georgia; hexahedrite; Ni-Co 5.70 percent, P 0.30 percent. Schreiber- 

 site needles showing apparently an iron-phosphide eutectic structure. That seems more 

 clearly true of the larger needle; the appearance of the smaller one suggests a stain pattern. 

 Such a structure in this case would probably be primary, forming as the mass cooled, 

 and not a product of reheating. The light etching with picrate alone reveals no structure 

 in the kamacite groundmass. Neutral sodium picrate 5 minutes; X ISO. 



2. Cedartown. An angular schreibersite body with a reticulated stain pattern. The 

 same etching as the preceding; X 600. 



3. Helt Township, Indiana; coarsest octahedrite; no analysis. A schreibersite inclu- 

 sion with a eutectic structure which is refined and uniform. It apparently originated in the 

 gamma phase, slow transformation permitting an orderly absorption of the excess of iron 

 from the iron-phosphide solution into the surrounding mass with no droplets of iron rejected. 

 The etching reveals no structure in the kamacite. Light neutral sodium picrate; X 150. 



4. Kendall County, Texas; granular hexahedrite; Ni-Co 6.42 percent, P 0.34 percent. 

 Part of an inclusion of schreibersite showing a reticulated stain pattern. Light picral and 

 neutral sodium picrate; X 600. 



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