Plate 2 



1. Arispe, Mexico; coarsest octahedrite; Xi 7.04 percent (Whitfield, in Ward, 1902). 

 The pattern is more regular than in many coarsest octahedrites. The kamacite bands aver- 

 age 3 or 4 mm. wide, though some are as wide as a centimeter (e. g., in lower right of photo- 

 graph. In many places two or more bands having the same oriented sheen are grouped 

 together in a fascicle, separated by very tenuous taenite lamellae. There apparently is no 

 plessite. Macroetch; three-fifths natural size, ordinary light. 



2. Santa Luzia de Goyaz, Brazil; coarsest octahedrite; Ni-Co 6.23 percent (Meen, 

 1939). This, like Sandia Mountains (plate 1), is a transitional type. Though containing 

 even slightly less nickel-cobalt than Sandia Mountains, it contains an appreciable amount of 

 taenite, and in the upper part of the photograph an octahedral pattern is clearly discernible. 

 The microstructure in general is typically hexahedral (plate 4). Owing to the coarseness 

 of the structure, the analysis perhaps indicates a somewhat lower nickel-cobalt content 

 than the actual average for the entire mass. Two large rosette inclusions of schreibersite 

 orcur in a large rounded area of kamacite. Macroetch; three-fifths natural ^ize. U. S. 

 National Museum. 



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