Plate 63 



1. Wichita County, Texas; coarse octaliedrite. Colienite is vevy abundant in this iron, 

 the photograph showing its characteristic form of occurrence as elongated inclusions within 

 the kamacite bands. The troilite inclusion is surrounded by graphite, schreibersite, and 

 some swathing kamacite. Macroetch; X l^:,, ordinary light. 



The analyses of Wichita County are not satisfactory. Cohen and Weinschenk (Meteor- 

 eisen-Studien \-ol. 6, 1S91) reported \i 7.93 percent, Co 0.40 percent, with no carbon or 

 phosphorus, the sample anahzed e\-idently having been free from inclusions. Analyses by 

 Manteutfel cited by Cohen (Ibid. vol. 7, 1892) gave Ni 6.74 percent, Co 0.59 percent, and P 

 0.03 percent; while another analysis ga\e calculated proportions for the whole mass as Ni 

 8.62 percent, Co 0.72 percent, P 0.97 percent, and C0.31 percent. The last nickel percentage 

 seems too high. A fair estimate for the mass would be Ni about 7 percent, Co about 0.50 

 percent, a substantial phosphorus content, and a relatively high percentage of carbon. 



2. Wichita County. Cohenite enclosing schreibersite, the latter showing black spots 

 due to surface chipping. Boiling alkaline sodium picrate 1 minute; X 60. 



3. Wichita County. Irregular schreibersite body intergrown with cohenite. Picral 10 

 seconds and electrolytic alkaline sodium picrate; X 60. 



4. Canyon Diablo, Arizona; coarsest octahedrite; for analyses see plate 64. Murikami's 

 reagent boiling, 10 minutes; ,• 60. The cohenite is not further darkened appreciably bv 

 longer immersion; it is slightly darkened with 5 minutes' application. With this reagent 

 scratches are brought out conspicuously. Although this, sample was polished with an 

 exceedingly fine magnesium oxide, used for metallograj)hic polishing of soft metals, the 

 scratches could not be eliminated. 



183 



