106 E. & Howell— Ainsworth Meteorite. 



corner exhibits the coarse octahedral structure, while the frac- 

 tured side has the appearance of columnar structure, and there 

 seems to be considerable tendency to columnar fracturing at 

 this particular part of the iron, columnar-like pieces breaking 

 from the sections as they were cut. Eight sections have been 

 cut all parallel to the first — the one figured. The principal 

 veins and the mixed figures of troilite and schreibersite con- 

 tinue through them all : in addition, however, three typical 

 nodules of troilite were encountered, which contrast strongly 

 in color and form with those in which the schreibersite forms 

 a prominent part. The sections etch very slowly ; in time, 

 however, lines appear which I did not hesitate to call Neumann 

 lines until Mr. Tassin proved the iron to be an octahedrite, as was 

 at first indicated by the fracture. These lines do not cross the 

 veins referred to, and they are differently oriented in each of the 

 blocks outlined by these veins, making the blocks appear as 

 separate units. Mr. Tassin finds the structure of this iron to 

 be unique, although in general appearance — especially in the 

 irregular graphic segregations of schreibersite and troilite — 

 it very closely resembles the Sao Juliao, and in a less degree 

 the Tombigbee River, and in some respects the Kendall County. 

 Mr. Wirt Tassin of the IT. S. National Museum has devoted 

 considerable time to the study of this iron and gives a sum- 

 mary of his results as follows : 



Analysis and Notes on the Ainsworth Meteorite, 

 by Wirt Tassin. 



Meteoric Iron from Ainsworth, Nebraska. 



The iron (fig. 1) here described is triangular in outline and 

 shows a well-marked octahedral fracture on one edge, in fact the 

 three edges of the section approximate three directions of an 

 octahedron with the cut surface forming a fourth, giving the 

 mass as a whole the appearance of a flattened octahedron. The 

 surface as cut shows octahedral lamellae of the largest size, so 

 large that they are not at once apparent, as the specimen is not 

 big enough to contain more than a few of them. Careful etching 

 develops a surface having in places a mottled or dappled appear- 

 ance. These mottlings when magnified under a vertical illumina- 

 tion show a definite octahedral structure and an etch figure 

 (fig. 2) directly comparable with that of other octahedrites, and 

 may be regarded as centers of crystallization, which though 

 minute, possess a well-defined lamellar structure and usually 

 show the three characteristic alloys. The accessory constituent, 

 shown in the figure as rows of crystals in relief, is unknown but 

 is here assumed to be nickel-free iron. Such a structure, a most 

 coarse octahedrite containing very minute octahedrites, has 

 never before been observed by the writer. Contained in the mass 



