Plate 7^ 



1. Canyon Diablo, Arizona; coarsest octahedrite. Many examples of deformatior 

 have been observed in this iron. The figure shows a plessite field with two displacements. 

 Picral 50 percent, nital 50 percent, 12 seconds; X 45. 



2. Canyon Diablo. Displacement running through a body of cohenite and a field of 

 lamellar plessite. Picral 50 percent, nital 50 percent, 12 seconds; X 45. 



3. Canyon Diablo. A displaced lamella of taenite. Owing to the ductilit\'of the taenite, 

 a thin layer connects the separated portions. Picral 50 percent, nital 50 percent, 5 seconds; 

 X 150. ' 



4. Canyon Diablo. Portions of two different plessite fields. The displacement may 

 have been in two directions with respect to the plane of the section. Picral 50 percent, nital 

 50 percent, 12 seconds; X 45. 



This peculiar plessitic structure was referred to by Vogel as a phosphide eutectic, with 

 illustrations from Canyon Diablo and Toluca (Tiber die Strukturformen, etc., Abh. Ges. 

 Wiss. Gottingen, math.-phys. Kl., new ser., vol. 12, No. 2, p. 23, figs. 31, 32, 1927). It 

 seems, however, to be clearly a gamma-alpha nickel-iron structure of an imperfect pearlitic 

 pattern, similar to that observed in Otumpa, Leeds, Seelasgen, Youndegin, and other irons. 

 The graying of the gamma component (taenite) by reason of supersaturation is apparent 

 in this photograph, and still more so at higher magnification, which also shows the alpha 

 component to ha\'e a structure similar to that of the surrounding kamacite. 



