Plate 48 



1. Seneca Township, Michigan; finest octahedrite; Xi-Co 11.67 percent. Hexagonal 

 crystal of troilite about 3 mm. in diameter. Its planes are unrelated to the surrounding octa- 

 hedral structure. Macroetch; X 9, ordinary light. 



2. MoNAHANs, Texas; nickel-rich ataxite; Ni-Co 11.51 percent. Troilite inclusion show- 

 ing definite hexagonal angles, bordered by an irregular band of swathing kamacite. Picral 

 40 seconds; X 60. 



3. Otumpa, Argentina; hexahedrite; Xi-Co 5.68 percent. One of several minute highly 

 perfect crystals of troilite observed in this iron. The triangular shadings may be due to 

 variations in the attack of the etchant according to the directions of the crystallographic 

 planes. Light picral; X 60. 



4. Hex River Mountains, South Africa; hexahedrite; Xi-Co 6.34 percent. An inclusion 

 of intergrown troilite and daubreelite, with two schreibersite needles (lamellae). The 

 lighter bands are daubreelite, the darker troilite. The former, more resistant to etching, 

 reflect more light than the latter. The occurrence of these two substances in a banded 

 pattern is not uncommon. Picral; X 60. U. S. Xational Museum. 



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