VI BULLETIN 184, UNITED STATES NATIONAL MUSEUM 



An eclectic iron-nickel diagram 40 



Comparisons with the iron-carbon diagram 41 



Hysteresis increased 42 



A meteoric iron-nickel diagram 43 



Bradley and Goldschmidt's diagram 44 



IX. Meteoric nickel-iron 45 



Structural changes 45 



The trias summarized 47 



Crystallization in meteorites 48 



Granulation 49 



Composition of kamacite 51 



X. Hexahedral structures 52 



Classification 52 



Neumann lines 53 



Taenite and plessite 53 



Transitional types 54 



XI. Octahedral structures 54 



Genesis of the Widmanstatten structure 54 



Fineness of octahedral structure 56 



Vogel's theory 57 



A low-temperature equilibrium 59 



Cosmic heatings 60 



Transformation structure 60 



"Spotted" taenite and kamacite 61 



The "ragged" structure 62 



Granular octahedrites 63 



An anomalous iron 63 



Transitional octahedrites 64 



XII. Plessite; nickel-rich ataxites 65 



Genesis of plessite 65 



Vogel's views 66 



A two-phase structure 67 



The nature of kamacite needles 68 



Recapitulation 69 



Spheroidized taenite in plessite 69 



XIII, Heat alterations 70 



Artificial heating 71 



Natural reheating 71 



Nickel-poor ataxites 75 



Cosmic thermal changes 76 



XIV. The role of phosphorus in meteoric iron 77 



Schreibersite 77 



Phosphide in taenite 78 



Schreibersite and troilite 78 



Diffusion of phosphide 78 



Iron-phosphide eutectics 79 



Effects on i)hase transformations 80 



Genesis of phosphide inclusions 81 



Phosphorus and plessite 81 



Studies on the Cape iron 82 



References 83 



