Plate 46 



1. Leeds, Quebec; medium octahedrite, no analysis. The specimen, locality unknown, 

 came with other minerals from Leeds and was recognized in 1937. A plessite field showing 

 spheroidized taenite and (lower left) small areas of pearlitic structure. Picral 60 seconds; 

 X 60. 



2. Otumpa, Argentina; hexahedrite; Ni-Co 5.68 percent. A plessite field of unusual 

 character, the clear kamacite interior containing spherules of taenite, some of them showing 

 dark cores due to incomplete transformation. The surrounding taenite border is gray in 

 places because of supersaturation. The broadened border at upper left consists of dark 

 plessite with a pearlitic structure. Schreibersite inclusion, upper right. Very similar 

 fields are found in Seelasgen and Youndegin. Otumpa was classified by Brezina and by 

 Cohen as a nickel-poor ataxite, and is still so listed in museums. It is actually a granu- 

 lar hexahedrite, in many places showing a profusion of Neumann lines, and numerous 

 plessite fields of various structures. (See pi. 44.) Light picral; X 60. 



3. Seelasgen, Prussia; coarsest octahedrite; for composition see plate 38. A plessite 

 field amost indentical with that shown in figure 2. The spherules are smaller and more 

 numerous and the dark plessite with pearlitic pattern more abundant. Small schreibersite 

 bodies In the field and along grain boundaries at upper left. Picral 60 seconds; X 60. 



4. Seelasgen. Part of the area shown in figure 3. In the border the pearlitic plessite 

 abuts against gray taenite. Picral 30 seconds; X 3(X). 



KJG 



