Plate 5 



1. Fort Duncan, Texas; hexahedrite; Ni-Co 5.87 percent, P 0.23 percent. Typical 

 structure of a "normal" hexahedrite, with very abundant rhabdites; two sets of Neumann 

 lines. Picral 75 seconds; X 30. 



2. Fort Duncan. Rhabdites give place to very long oriented schreibersite needles 

 (lamellae) and a dispersion of minute phosphide particles. The particles, as usual in such 

 cases, are absent in the immediate vicinity of the lamellae, the growth of the latter having 

 absorbed the phosphide from the surrounding mass. Picral 75 seconds; X 30. 



3. Indian Valley, Virginia; hexahedrite; Ni-Co 6.09 percent, P 0.27 percent. This 

 iron, prevailingly "normal" in structure, nevertheless is marked in some places by scattered 

 grains with a strong sheen, appearing like snowflakes. Two such grains are shown in the 

 photograph. The directions of the Neumann lines indicate the different orientations of 

 their planes which give rise to the variable sheen. Picral 60 seconds; X 60. 



4. ToMBiGBEE River (Desotoville), Alabama; hexahedrite; Ni-Co 4.78 or 5.01 percent. 

 A finely granular hexahedrite with Neumann lines variously oriented in the grains. A needle 

 (lamella) of schreibersite, the black marks due to surface chipping. Light picral; X 60. 

 U. S. National Museum. 



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