414 PROCEEDINGS OF THE NATIONAL ]VIUSEUM vol.90 



iron in the Chicora was determined by recalculating the analysis of 

 the acid-soluble portion and averaging the results. The metallic iron 

 present was so determined to be 2.65 percent of the total. 



It is difficult to understand why the coarse material should contain 

 more nickel than the fine-grained portions. Nevertheless, table 7 

 shows that in each case two determinations were made and the results 

 agree very nicely for each portion. Confidence can be placed in the 

 figure given for the nickel, but, since iron is difficult to separate from 

 cobalt, there may be a large analytical error in cobalt values. The 

 ratio of nickel to iron is 1 to 2.68, an unusually high nickel content. 

 The nickel content of hexahedrite irons is about 5.5 percent, while 

 octahedrites average from 6 to about 12 percent. Farrington ^ lists 

 22 analyses of taenite, and the range in composition is so great that 

 little satisfaction can be had by referring to his table. The range of 

 taenite extends from Fe, 86.44 percent, and Ni, 13.02 percent, to 

 Fe, 50.73 percent, and Ni, 47.8 percent. 



Prior,^ in discussing the relationship between the nature of the 

 nickel-iron to the magnesium silicates in meteorites, says: "It was 

 found that a progressive change m the chemical composition of the 

 nickel-iron and of the magnesium silicates could be traced from chon- 

 dritic stones like Daniel's Kuil containing over 20 percent of nickel- 

 iron to those like Soko-Banja containing only small amounts." He 

 further states: "The less the amount of nickel-iron in chondritic 

 stones, the richer it is in nickel and the richer in u'on are the mag- 

 nesium silicates." The Chicora meteorite agrees with this observa- 

 tion of Priors. 



There are now a number of different observations on record that 

 many stony meteorites are apparently of clastic origin. There are 

 also indications that the metallic portions of meteorites are later 

 introductions. If that be true, the agreement in the mineralogy of 

 the Chicora meteorite with Prior's suggestion may be nothing more 

 than accidental. It will require the compilation of much data before 

 this point can be properly settled. The Chicora meteorite certainly 

 supports Prior's statement. 



TEXTURE OF THE CHICORA 



Olivine and hypersthene are present in sizable masses, distributed 

 thi'ough a fine-grained ciystalline ground mass. The hypersthene 

 has a fibrous habit and is present as fragments of chondrules. The 

 olivine is also present in fragments of chondrides, but some of it is 

 encountered in subhedral inclusions. 



The structm-e of this meteorite seems to indicate a clastic origin, 

 and very little can be interpreted from the structure. Some evidence 



« Farrington, O. C, Meteorites, p. 134, 1915. 



« Prior. Q. T., Min. Mag., vol. 18, No. 83, p. 26, 1916. 



