Feb., 1906. The South Bend Meteorite. 21 



to be 3.35 and that of nickel-iron to be 7.70, the ratio of chrysolite 

 to nickel-iron by weight in the meteorite indicated by this specific 

 gravity is: — 



Chrysolite 78.63 



Nickel-iron 21.37 



100.00 

 This result is necessarily too high for the chrysolite and too low 

 for the nickel-iron as regards the original constitution of the mass, 

 on account of the fact that some of the original nickel-iron has 

 altered to limonite, and some of the pores contain more or less sand. 

 What change should be made in the above figures on this account 

 in order to express the actual original composition of the meteorite, 

 however, it is impossible to determine, but it is hardly likely that 

 a change greater than 5 % should be made. 



A piece of the meteorite weighing about 220 grams was removed 

 by sawing, giving a section having a surface about 2 inches square 

 available for study. The appearance of this section is shown in 

 Plate XVII. As indicated by the external characters, the interior of 

 the mass proves to be a sponge-like body of nickel-iron, the pores 

 of which are filled with chrysolite. The shape of the pores tends 

 to be rounded or polygonal, but is occasionally elongated or quite 

 irregular. A diameter of about half an inch (12 mm.) is a common 

 one for the pores, and they rarely exceed this. The distribution of 

 the nickel-iron is rather uniformly tenuous but occasionally bunched 

 so as to give a square centimeter of surface without chrysolite. 

 The walls of the pores as seen after removal of the chrysolite are 

 sinuous rather than angular and have smooth surfaces. A black 

 graphitic layer about .1 mm. in thickness usually lines the pores, 

 separating the nickel-iron from the chrysolite. A similar layer 

 occurring in the Mount Vernon meteorite has been described by 

 Tassin.* Etching brings out well-defined figures on the nickel-iron 

 showing that it is made up of the usual alloys of kamacite, taenite and 

 plessite. The kamacite bands are swollen and very variable in width, 

 but rarelv exceed 2 mm. in this direction. For the most part the bands 

 tend to border the chrysolite blebs, following their outlines in vary- 

 ing course. Bordering the kamacite on the side opposite the chry- 

 solite occurs a thin ribbon of taenite appearing and disappearing 

 without regularity, but for the most part quite constant. The 

 plessite, dark gray in color, fills the spaces between the kamacite 

 bands, resembling in its irregular shapes, the hieroglyphic figures 

 assumed by schreibersite in some of the ataxites. At times its 



*Proc. U. S. Nat. Museum, 1905, vol.xxxiii, p. 216. 



