Plate 1 



1. CoAHUiLA, Mexico; hexahedrite; Ni-Co 6.37 percent. A typical example of a "normal" 

 hexahedrite, showing no structure except Neumann lines, which run without change of direc- 

 tion throughout the mass. This is one of the Coahuila group of irons known as Sanchez 

 Estate. Macroetch; three-fifths natural size, ordinary light. U. S. National Museum. 



2. Sandia Mountains, New Alexico; granular hexahedrite; Ni-Co 6.45 percent (Hen- 

 derson, 1939). This iron is transitional between hexahedrites and octahedrites and, like a 

 number of similar irons, has been classed by some as a coarsest octahedrite. Inasmuch as 

 the composition and microstructure are t}'pical of hexahedrites, and no clear octahedral 

 pattern is recognizable, the author would class it as a hexahedrite. Compare Santa Luzia, 

 plate 2. Macroetch; three-fifths natural size. U. S. National Museum. 



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