Plate 9 



1. Chesterville, South Carolina; nickel-poor ataxite; Ni-Co 6.55 percent. General struc- 

 ture, showing rhabdites and phosphide particles, deformed and partly diffused by heating. 

 Fine irregular secondary granulation. Light picral; X 60. U. S. National Museum. 



2. Chesterville. Schreibersite needles partly diffused, with iron-phosphide eutectic 

 cores and thornlike projections where liquefied phosphide penetrated the surrounding iron 

 along grain boundaries. It resembles the structure in the zone of alteration in Rio Loa. 

 Light picral; X 60. 



3. Forsyth County, North Carolina; nickel-poor ataxite; Ni-Co 6.08 percent. General 

 structure, a profuse dispersion of minute shapeless phosphide particles in indistinctly 

 granulated kamacite. The particles are attacked even with very light etching (3 seconds) 

 and are quickly obliterated, leaving black spots. Picral 45 seconds; X 45. 



4. Forsyth County. Area adjacent to a large troilite inclusion, the penetration of the 

 sulphide along grain boundaries making them much more distinct than in the iron as a whole. 

 The ragged edge of the inclusion, and extensive penetration of the sulphide into the iron, 

 indicate a much longer and higher heating than the atmospheric heating that produces zones 

 of alteration. Picral 45 seconds; X 45. 



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