Plate 32 



1. Limestone Creek. Structure in the central part of the slice examined. Unetched; 

 X 60. The gray component, though it might appear too gray for oxide, is shown in the 

 next photograph to be such. Field Museum of Natural History. 



2. Limestone Creek. Part of the area shown in figure 1 at high magnification. The 

 gray component in figure 1, appearing in delicate branching forms, is here seen to be oxi- 

 dized kamacite particles. The groundmass shows no structure. Unetched; X 600. 



3. Limestone Creek. An area somewhat similar to figure 2. Light etching develops 

 the two-phase structure of the groundmass, the gamma phase predominating, the alpha 

 (kamacite) areas in part oxidized. Picral 10 seconds; X 600. 



4. Limestone Creek. At this place, near the edge of the slice, oxidation was stronger 

 than in the preceding figures. The needles of kamacite though surrounded by taenite are 

 darkened, as well as the* kamacite of the groundmass. L^netched; X 600. 



l.->2 



